You can track the changes in rules in a bounty campaign by checking the thread itself and if the project has telegram groups, it is commonly posted there so I don't think you should worry about it. The only problem you're going to have is being active or not.
Most of the new rules are usually placed on the OP of the bounty thread most of the time and a lot of them now always tend to have telegram announcement group which anyone can join so as not to miss the chances of getting important updates on any project they are participating in.
The latter is what I have always made use of actually for a while now except once in a while that I may just have to visit the OP at least once in a week like you said, to see if there is actually anything. For people that do not check often and for some project bounties that do not announce when they end, now I see the reason why some people would keep submitting report even when the bounty has ended few months back.
