I four bet one guy 3 times in the last session I played the other day and only 5 4-bets in total the entire day. His fold to my 4bets percentage was exactly 0%.
First hand aipf my QQ>A2dd.
Second hand, bvb he flats my 4bet from the BB with ATo and shoves when I check K77 flop with 77.
Third hand, I called a semi-lag's CO raise from the btn with AA hoping to induce a squeeze from one of the two agro blinds. SB in fact squeezed, I shoved and my AA<QQ.
I'm getting huge action right now with not only my 3-bets, but my 4-bets and 5-bets. So, I've basically just shut down with the 3-betting light from the blinds and 4-bet bluffing. Hopefully they'll never notice
Edit: I think if you just continue to steal in late position, and iso raise limpers light you'll project an image that gets you lots of action in re-raised pots. (In MSNL at least)