Against some opponents I might look to check behind the turn and c/c down, usually against the sort of player who likes having the initiative and calls flops with the intention of bluffing later streets. But against my opp., who calls down with middle pair and any Ax (that's any Kx and any Ax), which bit of his range that I might get value from on the river does he fold to a turn bet?

I like the flop bet size but I don't like the turn sizing
Do you think a smaller bet is more likely to string him along? Is it to do with betting less in case he raises?