We need to clarify certain key concepts in order to answer this question.
What is a word（詞）in the Chinese language?
A "word" in Chinese is officially defined as the smallest unit of speech that can be utilized independently. 最小可以獨立運用的語言單位。
While many words are in fact morphemes 語素 expressed by a single mono-syllabic character (such as 我、吃、飯 etc), there are many exceptions.
Some of the most typical examples are the unbroken words or 聯綿詞. These are words such as 葡萄、鸚鵡、叮噹 etc. These words often consist of characters that are phonetically related by alliteration 雙聲 （琵琶、玲瓏）, rhyme 疊韵（蜻蜓、逍遙）or both（輾轉、鄭重）. Most, if not all of the onomatopoeia 擬聲詞 (嘩啦、乒乓) also fall into this category. Some of these words can be up to four characters in length（唏哩嘩啦、嘰裏咕嚕）.
A quick illustration before we move on: 嘩啦 is a word; 唏哩嘩啦 is also a word that consist of the morpheme 唏哩 prefixed to the word 嘩啦. 唏哩 is a morpheme (which serves to modify or constrict the meaning of 嘩啦) but not a word, because it has no usage and meaning independent of 嘩啦.
Is 平板電腦 a single word?
平板電腦, in this case, can be considered one compound word 複合詞 (because it is a single noun), consisting of the "morphemes" (which are, in fact, words) 平板 and 電腦 (like mobile phone in English, but pieced together to form a single word, mobile-phone), the former can actually be used as an abbreviation of the full noun.
It is convenient, semantically, to consider a noun as a single compound word in Chinese, even though it can be further broken down into more basic word-units that very often boil down to the individual characters.
Since a noun can have many nested qualifiers, we will find long constructs such as: 北京中央电视台春节晚会演员休息室 which qualifies as a single compound word for being a single lexical unit that should not be broken up, and can be independently used as a part of speech.
How to read long words
In modern Chinese, the basic compound word unit is often determined by prosody (C.f. @lilysirus's answer above), which defines the prosodic word 韵律詞 that forms a basic 2-beat pattern or foot by which bi-syllabic compound words are constructed. So a compound word of four syllables would be 2 feet: [平板][電腦]. Words with one or three syllables would be respectively considered a degenerated or super prosodic word [聽/][收音機] that can be incorporated into the 2-beat rhythmic system.
It should be noted that the prosodic word must not be longer than 3-syllables and should be distinguished from the lexical definition of a word because we commonly have 4-character idioms 成語 that must be taken as a single lexical unit, but must still fall into a 2-beat pattern when spoken out loud: [裡應][外合]、[我行][我素].
In principle, long words or phrases should all fall into the prosodic 2-beat pattern and read in groups of 2-3 syllables which respect the lexical word boundary. Therefore, there should not, for example, be a long pause between two feet in a 成語: [坐井]#[觀天] - unless you are a language teacher anticipating your students to fill in the blank.
In the case of the long noun cited above, this should be read like so:
Words nest together can be read at a slightly hastened pace on a single beat. A regular bi-syllabic rhythm that is blind to semantics would not work:
It would definitely sound very awkward and mind-boggling if words were grouped together in a rhythm which violates lexical boundaries like so:
Some Additional Notes about Prosody
After a lengthy discussion with @lilysirus, here is my take on the issue:
- Prosody is a study of linguistic functions such as intonation, stress, and rhythm in speech.
- The basic rhythm of speech is defined as the foot, which, in the case of Chinese, would be the bi-syllabic Prosodic Word 韻律詞. This gives us a basic [DUM-dah] rhythmic pattern in verbal Chinese.
- According to Feng Shengli, the foot is by definition 2 syllables because stress (輕重抑揚) is involved in rhythmic patterns, and this can only be apparent when there is contrast between a pair. 「音步非二分不足以表抑揚」
- The assumption that the bi-syllabic foot "only applies to modern Chinese" is wrong. Feng has not made that distinction in his classic study 《漢語的韵律，詞法與句法》 and there are many examples to show that a comprehensive reading of classical Chinese does involve a basic rhythmic pattern of 2-3 syllables. Ex. 「[學而]#[時/[習之]]，[不亦]/[悅乎]？」「[白頭]#[搔/[更短]]，[渾欲]#[[不勝]/簪]」.
- The prosodic word is a very specialized theory that works pretty well to explain certain phenomena in the construction of compound words in modern Chinese, but is limited in the task of delineating meaningful lexical constructs and should not be used in place of the semantic and syntactical definition of a word.
- Take, for example 漢語大辭典, cited by @lilysirus above. This would naturally form the following triple 2-beat rhythmic pattern when read: [漢語][大辭][典#], which, seriously speaking would not sound funny to the native ear at all. A more lexically-informed reading, however, would be: [漢語]/[大辭典] (with the latter word forming a triplet in 2/4 a rhythm), or even more precisely [漢語]#[大/辭典]. But an apparent long and short pause in between would actually sound awkward when spoken out of context. (So, @lilysirus claims that it's "not even detactable by ear". In other words, its a theoretical construct.)
- The reason why 漢語大詞典 is preferred over *大漢語詞典 can, indeed be understood as follows: Given the basic 2-beat foot that forms a prosodic word, 大 must be closer to the noun which it modifies (it is the dictionary that is "big", not the language) than one which it does not. However, there are similar lexical constructs that are very common in modern Chinese, such as 大東北地區, which can very much be a 1+4 or 1+2+2 (but is actually a 3+2), and is preferred over *東北大地區. 大地區, when implied, is almost always abbreviated as 大區 (as in 東北大區). The difference is because 大東北 is a meaningful word, but *大漢語 is not. So it still boils down to semantics and syntax, but prosody informs how compound words can be constructed out of the 2-3 syllabic foot or prosodic word.
- There is no hard and fast rule that explicitly forbids a 1+4 or 1+2+2 lexical construct in Chinese - modern or otherwise. In prosody, the mono-syllabic leading-word can be read with a pause, like: [究/][天人]/[之際]、[先/][天地之][憂/][而憂]; modern Chinese of a similar lexical construct can be read the same way as well: [別/][欺人][太甚]、[請/][注意][安全]. The leading word can also start on a light up-beat to stress on what follows: [/別][欺人][太甚] (i.e. Don't be a bully!, Vis-à-vis Don't be a bully!)
- The prosodic foot should respect lexical boundaries as much as
possible to avoid sounding monotonous (in the case of a steady and
constant-speed bi-syllabic flow) or misunderstanding (in the case of pausing in at position where there should not be a one).