Why wouldn't you bet as you often have the best hand? What are you trying to achieve if you check the turn?

Maybe we want to have some stronger hands in our check range, and if we get it in here, we are not gonna be in good shape that often right?
To me this looks like the perfect kind of hand that wants to see the river but doesnt really want to get it in on the turn.

Why do we want to include stronger hands in our checking range, as this looks like a situation where our range is a lot stronger than UTG+1 range? And against fish do we even need to think about balancing?

Reg decides to check-call instead of cbet on draw heavy board. On blank turn he decides to check again after the fish, that doesn't look like a hand that is going to c-raise. If he has a strong hand, I would think he wants to build the pot when there is that fish in the hand instead of trying to keep it as small as possible.

I would bet for value, you won't get raised that often. And as the fish probably calls too, it means that reg can't turn his hands to a bluff that often on the river which gives you a chance to take the hand to a showdown is you prefer so.