Am I just not doing it right or has anyone else noticed that the 'life' of a cart when you fill it yourself is significantly shorter than the pre-filled carts? When I first got my penstyle, it came with the usual pre-filled cartridges. I also ordered some extras. Those carts lasted me, literally, all day. Put one on in the morning and good to go until bedtime. However, my supplier closed up shop (thank you SO much Health Canada!) so started refilling them myself. Seems like no matter what I try, I can only get about a quarter the amount of time before having to change out again. I fill them slowly, use a syringe, use a dropper, let them sit for awhile and top up ... everything I can think of and it's still the same. Anyone else experience this? What is it they do with these pre-filled ones that makes them last so much longer?