Villain is 61/14 with pretty aggressive postflop stats.

PokerStars No-Limit Hold'em, $0.25 BB (6 handed) - Poker-Stars Converter Tool from FlopTurnRiver.com

BB ($19.60)
Hero (UTG) ($28.90)
MP ($23.75)
CO ($26.15)
Button ($25)
SB ($25)

Preflop: Hero is UTG with 8, 8
Hero bets $1, 4 folds, BB calls $0.75

Flop: ($2.10) 3, 10, 4 (2 players)
BB checks, Hero bets $1.75, BB calls $1.75

Turn: ($5.60) 2 (2 players)
BB bets $2, Hero calls $2

River: ($9.60) J (2 players)
BB bets $4, Hero calls $4

Total pot: $17.60 | Rake: $0.85

I'm not sure what his small turn donk means: it could either be a draw of some sort or a T. On the river I feel like he's really only repping JT or maybe 65 that was getting cute on the turn. Other than that, the J only helps his range if he had JsXs, but I would really expect him to check/raise an overcard+flush draw on the flop based on his aggressiveness.

You could make a case for raising the turn. As played, however, I think a T is checking a lot of rivers while a missed draw is bluffing a lot of rivers. If an obvious draw comes in, I'm not going to feel too bad about folding the river. If I raise the turn, however, most Ts aren't folding and are still checking rivers, but I'm setting up a bluff from villain on a scary river card for a big pot. I'd prefer to keep the pot small and re-evaluate the river with a hand that isn't much better than a bluff-catcher at this point.

So I made the gross-feeling call down in this spot, feeling like I was ahead often enough on the turn and then again on the river to call both times. My question is, against a laggy opponent, how often should we be making call downs like this? I really feel like we have to sometimes in order to avoid being exploited, but obviously we don't want to be making calls like this all the time. So is my play here bad? Is it okay to do this x% of the time? Any estimates on x?