Splitting the tape when opening a bag is THE WORST.
Truly the biggest monsters in the world of comic collecting are dealers who use two pieces of tape horizontally near the edges. I have a Swiss army knife next to where I read my comics specifically so I can use it to take any tape off that splits.
Whenever I see comics like that, I can't help but think that these are people who have never had to take the tape off of a sealer comic bag, because if they did, they wouldn't put the tape horizontally.
Numerous times I've considered starting a thread to rant about exactly that, but I never felt justified enough in doing so. But since it's just a post now, rather than a new thread, I can finally get it off my chest.
As for what I do, I buy self-sealing bags for my new comics, though it's really created a sense of hyper awareness when I read those comics, because I've ruined several and had to carefully peel others back to avoid damage when I left the flap open when reading and then would set the comic down right on the sticky strip. Now I always try to remember to close the flap after taking the comic out. (Special weird note that one dealer on here ships self-sealing bags with the sticky on the flap, which is so incredibly awkward to get comics out of, because I have to flip the flap into a circle and then stick it to the front of the bag.)
I generally leave second hand comics I buy in the bags I received them in, but I'm perfectly content to just tuck them in, though I take extra care to have as little of the flap fold inward when I do so.
My older comics that I keep in mylar bags I'm perfectly content to use one piece of vertical tape in the middle, those bags are sturdy enough that the flaps don't fold over unless you're making a concerted effort to do so.
When I ship comics out that I've sold on that one auction site, I use two pieces of vertical tape about 1-2 inches from the edge.