I did a rebuild of 4 cartos today and for what it's worth, the fact that I can only use a GO-cart 4-5 days before having to put it aside has nothing to do with the carto itself. As I have stated before I go through 4 plus ml a day of juice and literally keep the cartos and battery pretty warm.
I sacrificed a carto just to verify that in my situation, with my vaping habits, 4-5 days is reasonable. The coil was so gunked up, I am amazed it still produced vapor at all. My daily vape is a 50/50 mix of Tasty Vapor Atomic cinnacide at 80pg/20vg and DK Tab 100pg. I suppose the juice could play a part but at a mix that winds up 90pg/10vg, I doubt it. Both juices are light colored.
My only point is that different vaping styles can and do dictate the useful span between cleanings. Besides, at $3 per carto and whatever the cost of the juice, it is still more cost effective than a pack of analogs and a can of smokeless a day over that span. Just keep in mind your vaping style as well as the juice play a role in carto longevity. Just because others can get weeks and yours doesn't isn't necessarily an indicator of carto quality.