The rule for reclining is that the person in the seat has the right to recline. The societal norm is that they should do so gently. I have had people complain about my reclining on overnight international flights, which I think is over the top. I have never complained about anyone else reclining, and that is the golden rule. I don't argue with other passengers about it - it is FA business. And the space and ability to recline without a complaint is the main reason I try to upgrade as much as possible and frequent blogs like this to help me do so.