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Dumle, you are completely under-estimating the bluffing frequency or value bet frequency of a weaker hand on this river in my honest opinion.

You can argue that betting the turn is imperitive, however there are a couple of flaws in your extrapolation of his ranges.

Your range is : Naked Draws = 20% equity, Draws + made hands = 30% equity, Made hands that beat us = ~95% equity.

If villain never c/r the turn as a bluff and never bets the river with a worse hand, then as long as Naked Draws and Weaker Made hands + draws = ~2x Stronger made hands then your analysis is correct.

I however think there is some merit to dismantling this range slightly, also to disagree with the fact that he doesn't c/r with a weaker hand... Your definition of this player puts him squarely on the diagram where we should check the turn, however a more unknown player has more erratic tendencies. The diagram is slightly skewed to show that against an unknown player we should favour or at least give thought to the fact that there would be merit in waiting to the river. Not everyone would release middle pair here on the flop, not everyone would release a gutshot. "We may have Ah-x on the river" and Villain may try and bluff his way to the pot, we have played this hand in similar fashion to that of Ah-x and it could easily be perceived to Villain that we would fold this.

A lot of players will bluff this river given this situation, and there are a lot of hands that we are ahead of. Betting the turn also knocks out weak flush draws, weaker made hands that would have invested money in the river in the form of a c/c or a bluff which we can capitalise on.

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