Vwls... It may be that the reason you think cartos that sit for days are so good is because the juice is "steeping" in the carto... are you allowing your juices to steep in the bottle for a week or two, or just pulling them from vapemail and using them? Curious.
I've never needed to leave a "pre-holed" carto sit for absorption longer than a few hours. I plug the center hole with the shaft of a Q-Tip, literally fill the carto and let it set... repeat. At this point, the juice is leaking out the side holes and is ready to go. Never a burnt carto... knock on wood.... Some like to use the carto "condom" to force the juice into the filler... if you're in a hurry.
Although I own a very nice carto punch, I've never used it. I don't understand why anyone buys blank cartos when holed and slotted cartos are so readily available... unless you like a brand of carto that you can't get with holes. Boge (always available) and Ikenvape (when you can get them) are my favorites.
Consider buying Boge laser holed or slotted cartos. Slotted ones are nice for hi VG juice. SureVapes has nice pricing on 5 5-packs (25 cartos) for about $1.08 per.
That's all I got. Good vaping... with carto tanks of course. ;-)
C
Great point. I do a lot of DIY, but do order from vendor occasionally. Most of them are made to order juice makers so some steeping helps the flavors come out as well as blend in my experience. I do cheat a little by dripping a little right out of the mailbox though