Not quite; what I was thinking is that one man can complete a straightforward SEP Annual in one week.
Then, how many planes you can work on concurrently depends on the size of the premises. If you had a place big enough for four planes, then you would probably have four mechanics working there.
I suspect the #1 issue is that one doesn't get the steady business to keep the "line" occupied the whole time.
In practice, you would put two men on each plane. A lot of operations are much easier with 2 anyway. I have been using such a company; they do the Annual in 2-3 days.