Once we’ve checked three streets and hold a weak pair, we should usually just check back river and take the showdown instead of turning it into a bluff.
Monotone Ad2d6d is very good for BB’s range after a limp: they have every Ax and loads of suited trash. Our middle pair plus backdoor possibilities has showdown value but is vulnerable. Betting small for protection/value is attractive; checking is fine if we expect BB to stab often on later streets or to overfold vs aggression.
Turn Jh doesn’t really shift the dynamic – the nut advantage still sits with BB’s Ax and better 6x, while we have a medium-strength bluff-catcher. After flop checks through, both ranges are somewhat capped. Checking again is standard; betting turn would mainly fold out worse and isolate ourselves vs slowplayed Ax and better pairs.
River 8s bricks the frontdoor diamonds and a lot of gutshots; pot is tiny and BB has checked every street, so our 6x has decent showdown. Firing 3BB into 2.5BB doesn’t credibly represent strong value and runs into Ace‑high and random pairs that are incentivised to bluff-catch. Checking back and taking our showdown is cleaner.
Note: Betting more than pot on the river with a weak pair after three checks turns a reasonable bluff‑catcher into a bluff in a spot where we’re not folding out enough better hands.