You can't adjust the line to compensate for an "extra" 15-20 points. You as bookie can't shade the line 6 points high, to compensate. Ot usually means over. The question is good. I got burned on one tonight. I had NY/ utah under 98.5 in H2 that stayed under with the total even with the OT. I lost ( by a half point) on NY under 49.5 points for H2. I hate unders in NBA, because of OT.
NFL is different, usually just 3 points "extra".
I combat the OT by betting a lot of H2, I'll play into it, lean to over if OT seems possible. I'll play quarters too. I hate losing an under in OT, it really gets me.
I was off in Sherman's thread. I said 10%, answer was 6%. It sure seems like 10%, I thought my guess was on the high side.
I don't know how to predict a line with OT, but you can't tweak it a few points, that won't account for the extra 5 minutes. I look at the possibility of OT when betting, for sure.