Lots of things to balance:
- one’s own time–is it worth it to yourself to take photos to begin with
- one’s own time–is it worth it to yourself to attempt to take (and crop) the best possible photos that one can given their equipment/environment limitations
- other people’s time–to what extent should one be considerate of how much time it takes identifiers to wade through masses of lower quality photos (this includes researchers who have to examine every image to find the one’s that can be used for research–which benefits the organisms as well as contributes to scientific knowledge)
- cost of server space–to what extent should one be considerate of how much money it costs to store the photographs on the server (this would include consideration to those who donate their money to help maintain the service)
Not only does it takes one’s own time to post quality observations, it takes other people’s time (and money). You’re right, it really can add up! But the costs are not yours alone to bear.
I try to balance all of those considerations and I choose to not post my lesser quality images–especially of common things–that don’t really make a meaningful contribution to the greater good. And being very active in the #3 category (as well as the other three in the list), I do weigh other people’s time quite heavily in my decisions.