another h1b transfer

my hu*****and just did his h1b tansfer(rd 02/20 and pending). he's already started to work for a new comapny. Can he do another h1b transfer if he finds another job in the city i will work in.

In that case he will have two pending h1b transfer. Is it ok?

Let us assume his transfer got approved, can he do another tranfer immediately? I heard that to play safe, you must work for the new employer for at least half a year. Is that true?

Thanks in advance1`