Also even though a spot may be wa/wb, doesn't mean checking back is necessarily best. In a spot where the part of villain's range that is way ahead still calls a lot of cbets and may be passive enough not to c/r bluff or bluff turn (ex. with 33 here), cbetting is strictly for value. It's just not as clear value as KK on a Q74ss flop for example.
Given villain is really passive and will likely call with any Jx, FD and gutshot, and even potentially something like TT, and won't turn worse hands into bluffs too often on the turn/river, I often cbet these flops for value.
We just have to know why we're cbetting, and know what to do on various turns given how they affect our opponent's flop calling range and how our opponent reacts. Sometimes this is a double barrel for value, other times I'll check back and fold a river, other times I'll check back and call river, and other times I'm playing the more pot control-ish line of checking back flop and playing out a turn/river.