I mean vs general reg with unknown frequencies.
Okay, I see 2 problems with betting small, the first is that I don't think we want villain to get the odds to call flop with Ax, and he should have a fair amount of those in most situations, it has okay equity given the odds and it has showdown value.
If I would play check (bet 0bb) with those hands isntead of bet small, you would get even better pot odds with Ax, weak pairs, gutshots? I assume vs check you would check back Ax, weak pairs? So it means I would loose value comparing to bet small?
Even if your Ax has correct pot odds vs e.g. TT, it doesnt mean that TT will loose money with small bet, or win less money comparing to check. TT has 76% equity vs AJ, AQ (your best Ax), so it means it is a value bet. IF we would have e.g. KQ, then you can say if you bet 5BB you win less money than standard bet size, but the difference is that KQ still have > 50% equity with standard bet size and can bet more streets for value, and TT can't bet standard bet size for value.
Also if I bet 5BB into 22BB pot, I need 18.5% FE, which means you should be defending at least 90% range on flop because I will bet so small with GS, bdfd, hands like AQ, AJ. Do you think it is realistic that you defend 90% range on board which favors my range? So it means you have to defend many very weak hands which are drawing dead vs my range, or to overfold flop.
The other problem is that it is quite an hassle to construct three diferent ranges: bet small, bet big, x/c.
By the way, I would not have here c/c and c/r range. The idea is to bet small the hands which I would otherwise c/r or c/c, which means I will have c/f range. On such a board it will be probably around 10-20% c/f range. If it would be board where our range doesnt hit that good, then it makes sense to check/call and check/raise.
It is more complicated, but actually not too much. Since my current standard c/c, c/r is balanced (at least the best I could do), then I simply cbet small all those hands from c/c, c/r.