Is there a time limit to purging

[JG420]

I started making my own bho a while ago bc I got sick of wondering what was in my cartridges so I started making my own bho for that but began dabbing as well. Still an amateur although I have things pretty consistent, I have a regular glass extractor although I plan on getting a larger stainless steel or aluminum one, I use victor premium (14) , and a 2 quart vacuum chamber and pump. My question is regarding to evacuation or "purging" time is too long a thing? Do some strains just never get to "shatter" as in shatters like glass and some are just "pull and snappy" no matter what? I ask because my normal time is 20-24 hours but iv gone as much as 48 hours and I'm just wondering if my long evacuation process is what making it less hard or maybe even still hot enough? Essentially I go till there are no more bubbles or very minor reaction. O and also I try to keep my temp 100-110. Picture (left) is yesterday's batch, picture (right) is what is left from last weeks. Top picture is with no light behind them, bottom is against a window with light behind it. One last thing, the dark spots especially in the pic with light behind them, is it impurities? Or just oil from the fats of the plant or from other plant matter (leafs) I try to clip off all leaves b4 blasting. Can it be fixed with better butane? I have yet to try whip it or puretane which is supposed to be food grade which sounds promising. Or is it just normal and unavoidable?