I gotta do all the cans anyway for the site to despawn, so I just choose a route that minimizes travel time between cans. Respawns are totally worth doing the bad cans, the rare respawns in the same system even more so.
I record the ingame estimate, which AFAIK is usually slightly below jita buy.
I just had a corpmate check intact armor plates: 6.760mil ingame estimate, 6.930mil ingame jita buy.
I may not have a full understanding of it and this may be a temporary fluctuation, but my experience is that my jita buy contracts on explo stuff are usually worth slightly more than what ingame estimate said.