Fair enough but surely you should get more than ten tanks out of it?
I am one of those who believe, right or wrong, that coil life can be different for each of us dependent on many variables. I have never, ever run one set-up for a whole day and may use as many as 8 in a day. Sometimes a filled tank may just sit for 2 or 3 days. How much does that, a sweet juice, wattage used, and how I inhale play into coil life, I have no idea. That is why I began with "hard to proclaim" followed by a conservative estimate of "at least 10 tanks", not 10 tanks at most.
I am not complaining what life I get out of T8 coils nor advising op what they should get out of theirs. merely sharing my experience for what it's worth. At least you got a good laugh out of it.