Thin value bet on drawy boards against regulars , do you do it?

Lets assume the board is something like Jh-5h-2d and you have AJo , you are OOP and you have 100bb , a 15/12 regular with 100bb called your raise IP preflop , his range doesnt contain worse top pairs than AJ therefore you get value from second overpairs/pairs and flush draws , you know nothing about your opponent , he may reraise your cbet with his draws or he may not , if he reraise your cbet with his draws then you are on trouble , you cant vbet against this type of hand therefore your cbet was pointless , you can just check the flop and bet the two other streets to get value from the other hands , therefore when we bet the flop we do it only to price him with his draws.

Is it worth to take this risk against an unknown regular?

There is sometimes value in checking, not necessarily to induce a bluff but for someone else to value bet a worse hand KJ QJ and to control the size of the pot in case the flush draw hits. You can actually get value on all three streets allowing an opponent to bet a second best hand in a spot like this but you have to balance by playing some of your draws like this as well. Paying attention to your opponents bet sizing throughout your session is important.

If I really thought the guy was polarized, I would go for a check raise. He is in position, so generally I would credit him with a wide range and just c-bet. Hands like 99 and TT often float the flop, so there is value betting.

Check call to the river. Unless you will call if he shoved or 3 bet when you check raise on then flop. Keep the pot low. If he checks on the flop also. Bet for value on the turn or look for possible set.

Even he is a regular, why be afraid.

Its your duty to bet.