wonderful! thank you for the help. while i do get a few ideas its kind of hard to apply them due to infrequency and differing quality of available materials.
ive found the 5 minute mark to be my soak time by watching the color of the liquid. good to hear your experience falls in the quick to moderate wash times also.

"Not sure how much it will hold in mg/liter or if that is really the issue. Both the cannabis oil and the naphtha are equally miscible in one another at any ratio, so I'm thinking it will be more of an issue of how long it takes for the weakened solvent to dissolve the remaining material as the concentration of cannabis oil rises."

That was my underlying if some what convoluted question.
The top off sounds like a great way to keep the "fresh" naptha strength going.

THANK YOU!
without help and inspiration i would still be soaking in buckets of 70% iso. eewww.