This sucks, because usually 4th qt bets are without OT for US sports. 2nd halves and fulltimes are with OT. That is Las vegas rules.
But Bet365 with all the live betting markets had to change it. I am sorry to say it, but it is at least partly because of me. It was very easy to hit them few years ago, when they had the LV rules. It makes sense, as they have it now and I will tell you why.
The difference between totals for last qt and totals for game can be anything between 0-2 points. It depends how close the game is. In extreme situation (where bet365 does not post lines of course), the difference can be up to 10 points or so. I am talking about situation where it is 2 point game and Lebron has 4 seconds at home to tie game... But even the 0-2 points are huge difference on totals and for linesmaker it is nearly impossible to set the line right, because he can not only set the line for 4th qt by 2, 1.5, 1, 0.5 or 0 points lower. He has to count the overal sccore and change those numbers, as the game is constantly going in favor of OT or towards blowout. It is many possibilities. Different situation is if you have 10 point game where at the beginning huge favourite is losing [and OT is very probable still] and different situation is 5 mins to go and also 10 points game, where -15 pts favourite is wining.
I hope you see the point here. They have it in rules. They do not make a shot on you.
If you talk to God, you are praying; If God talks to you, you have schizophrenia.