Tank size..

[Zuki]

Im just curious as to why tanks are designed at an average of 3ml('ish)..?
Size? clogging? juice integrity?

 

[Xaiver]

It's mostly about the size of whatever houses the coil and then how big around they want the topper. They use those two measurements and then whatever is left is liquid space.

My kayfun holds about 4ml, and I can make it about 3/4ths of the day between fills... I typically don't though, I refill it when I change the battery.