I don't know anything about Sapphires ...
but ...I do know coils & 100% VG juices 
(well or what we refer to as 100%VG) 
and 
In my experience...
 I get pretty much the same amount of usage/time 
"out of " all coils before they are in "need" of cleaning ....3-4 days 
after that they just don't "work" well & are usually tasting off .
At least that is what I've found with all of the ones I use...
CE2, Vision, maxomizers, turbines, ego-t atty's,
 
so I stick to the ones that I can clean the coil 
on or cheap enough to toss in a few days .
It's just the Price We pay for " Sweet VG Vapes " 