ZeroNet is better at dealing with such sites now but it's still problematic when a site grows past a threshold where requestors need to be prompted to increase the size. Nodes that are just seeding don't automatically seed the changed site since they don't respond to the size change request.

One way of dealing with it is to make the images "Optional content". This means they are not sent to requestors of the site immediately - they are requested only when specifically wanted. Users can choose to seed optional files - in which case they'll mirror them all - or they only seed the ones they've looked at. Optional files don't count towards site size limits.