I've loaded rounds for several Garands, two M1As, a Mini-14 and two ARs and never had to use a small-base die. Military brass, commercial, 7.62x51, 5.56x45, .308, 30-06, .223 no difference.
My friend recently purchased an AR and he could not get a round to chamber after being F/L re-sized in a regular die. He borrowed a small-base die and no more issues.
From my experience it's basically a crap shoot if you need one or not.
I've loaded quite a few rounds for a couple of 223 ARs. Both functioned well with cases sized using regular dies. I did buy a set of SB 308 RCBS dies for the Rem 7400 I owned a while back. I don't know if it really needed it or not. I found that the SB dies basically size the brass to the dimension of new unfired brass. BT
I spoke with the folks at Hornady about this several years ago. They advised me their dies are generally cut to a smaller dimension than other brands and they do not, correspondingly, make SB dies. My minimal experience loading for my Browning BAR corroborates their statement, in that resized brass from that gun cycles through it after cycling through a Hornady FL size die. It could be a fluke, though, as I have not had opportunity to test beyond that rifle and set of dies.