中 is a redundant word when used in such context. Instead, you could write:
The reason why
中 is not used to express a period in time is because
中 has another meaning -
He failed his mid-year exam.
It is clear to Chinese native speakers when the context is given that the number of years refer to a period in time instead of a specific point in time. So there is no real need to add
十年 to express a duration.
However, if you really insist, you can use
来 instead to express duration.
He has never been home during the past ten years.