Definitely they do in most cases and the rewards are sometimes profitable. The only challenge there is that majority of the bounty participants would have exited the telegram channels of such projects before rewards are being released and by so doing may not benefit from it. It is always good to know the objectives and future prospects of project before one decides to participate in it so that if their is any need to wait for long, one will not hesitate to do so.It is also important to note that the fact that a project pays reward late does not mean it will be a profitable one as everything depends on the value of the project coin and sometimes on the kind of exchange in which the coin is listed.