the problem with upward jelq imo is that i think it creates a baseball bat effect, so u would also have to do downward jelq, which is to me is quite hard, so personally i haven't been really doing much jelq, although i've experimented with it many times
u ask about effectiveness. it depends how you're doing it. if it's a flaccid jelq, i think it would be a good warmup exercise to get the skin loosened up a bit and slightly stretched out but as far as a stretch exercise itself i don't know how effective it would be compared to other length exercises on this forum
if it's done erect, i think it's a good exercise to increase upper shart and glans growth. quite of few people have searched for ways to increase glans girth and i think erect upward jelq is good for this just based on personal experience when i was doing high intensity upward jelq i would get great glans expansion.