The adjective half-assed means to finish something but often without regards to it being perfect.
I don’t think 半途而废 means this as it literally means go half-way and give up (and not finish).
I recently found a word called 敷衍, but I remember I learned that it meant “patronize”. Like 别敷衍我了.
So what is a good word to describe someone who does stuff without giving a 100 percent of their effort?
Consider: 半吊子
Noun
半吊子1 (figuratively, colloquial, derogatory) one who lacks adequate knowledge or skills; dilettante; smatterer; dabbler
2 (figuratively, colloquial, derogatory) hot-headed or impulsive person; one who leaves tasks unfinished, or the tasks which are unfinished
Example from English du jour - online English classes available on Facebook
每日英語 : 海夫愛司 half-assed=[半吊子 <Everything he does, is half-assed. 他做什麼事情都半吊子。>]
敷衍 as an adjective or adverb can be used to describe a perfunctory attitude; consider the phrase 敷衍了事 (lit. to skimp through so as to finish something), or the idiom 敷衍塞責. Synonyms include 馬虎 and 草率, which are slightly more colloquial. As in, for example, 做事馬虎, 辦事草率. Or even 馬馬虎虎, but seldom 草草率率, nor 敷敷衍衍. 搪塞 also works, but only as a verb. If you want to comment on the lack of quality of someone's work as a result of their attitude, you may want to use these.
全力以赴, 盡力而為, 出盡全力, 用盡全力 and the like all describe the opposite; you may accuse (or rather, encourage) someone for not making their utmost effort by negation, such as adding 沒有 before these phrases. Or even 付出100%的努力 (lit. to pay 100% of one's effort, as stated in your question) is perfectly understandable.
For a more natural expression (if you wanna skip using chengyu) I would go with 敷衍. I wouldn’t use “patronize” as a translation except in very specific cases. 敷衍generally means when you don’t put your heart in sth or give much attention to sth (or someone for that matter). It could be used with both things (敷衍工作-work in a half-assed manner) and people, in which case it means giving a bare minimum of attention or seriousness to someone(closer to “patronizing”, like the example in your question 别敷衍我了).
You would hear 敷衍 in workplaces and schools/universities, sometimes as criticism （“他的工作过于敷衍” His work is sloppy) but more often in imperative and as a warning not to idle (“希望各位不要敷衍了事” Please do not work half-assed).
Some more colloquial choices are 应付 and 糊弄。You hear 应付 a lot from parents, teachers and bosses, it also means giving a bare minimum of input and attention and is just a more colloquial version of 敷衍。糊弄 expresses the same meaning but with a slightly deceptive undertone, like you’re trying to pass off something (unqualified) as something else, in an almost cheating manner.
half-arsed = sloppy = 马虎的
他无法忍耐同事们马虎的工作。
He can't stand sloppy/half-arsed work from colleagues. (sounds like the gf!)
他这个人做事比较马虎。
He tends to do things in a sloppy/half-arsed way.
