took previous Yo's OH a month (give or take) to build a 6 block & hay barn from rubble/weed mound - to us using it only doing evenings & weekends.
it was fantastic too, full eletrics, generator wired up ect.....
depends on what type of materials.I just had a block of 5 14x12 stables witha 10ft overhang from west of england stabling it took less than a week.Did a fab job and v reasonable.They are doing me tack room feedroom and barn when snow goes
We built our own stables and small barn, in blocks with an astbestos style (not real asbestos, of course) roof. It was almost as fast as getting somebody else in to put up wooden stables the same size!
Mind you, my partner was motivated by me screaming at him to get on with it and impending heavy rains! It was water tight in ten days, but frankly not fully safe for a month.