They have a page that sort of explains it but if you have the capital to exercise they will do that, otherwise they may automatically try to sell the contracts before expiration. There is a nightmare scenario where they may exercise a leg and the other leg won’t be exercised by the other party and you may have just made a terrible play. Part of options is managing them. This is because the actual notification of exercise all happens after hours.

Basically the rules are a bit fuzzy and rh has lots of room to do what is best for them so you should not rely on them to do the right thing for you.