Z coils are pretty good in my opinion but in my case I Vaped 70vg and desert flavours using 0.8coils...
i used to change those every week or 10days or few rare times even earlier like 5days cause I notice it got kinda tight to puff and taste started fade away...
but the thing is that if u remove and check it u see it will gunk up really early and makes sense with that little cotton packed inside those drop in coils...
I don't say it's bad to vape it that way but depends, someone may be sensitive to change of flavours...
The point is what juice u vape vg ratio , the flavours percentage, how hard u puff and how much u vape per day and the airflow u use blah blah blah and everything and I guess I was really stressing the coils also chainvaping a lot...
the slide topfill on my zlide became loose from first week and wasn't sealing that good causing to start to kinda flood the coils making the 0.8coil usable lower than 17watts cause it would spit and boil but not big deal for me
..now I convinced my gf to quit smoking and she uses the zlide and she is fine and the way she Vapes coils last her more than 2 weeks but I change them at 10-15 days cause ok 2.5euro per 10days I think it's ok

not even bother rebuild those coils
@UncleJunkle see I tried make paragraphs

I no spik gud eglis I trai Mai best thenx u