If I want to stop and end my session, well, IDK, it depends on how long I want to end my session usually if it's like a day, well, the ejuice is going to not go bad in a day. If I want to change flavors I just vape it down further. If I want to stash a tank or setup for awhile, sure, I'll aim for a moment where my eliquid is low, but I DIY so I don't fret overmuch about it, I mean, usually we're talking a lot less liquid to discard and it's less expensive.
I only get really irritated if I've filled up say, a 4.5 ml RTA with one of my favorite juices and the taste starts to go, and I have to discard everything but even then I am like, "Oh well." Etc.
You can vape your tank to pretty much empty using TC without fear of dry hits. I guess that would be an option if you have TC capable devices. You can also layer similar flavor profiles if you want to feel adventurous.
But stop vaping etc? I think it's fine if you are going to return to it in a few days, although the progression there if you don't clean your tank is gonna be, less flavor, eliquid turning to sludge, coil getting gunked, etc. So if you are ever like, headed to court and you think it won't go so well and etc., and you may have to "end" your session for awhile, I would recommend perhaps cleaning out your tanks.
There are also these handy dandy little syringes that you can pop into your tank and suck out all the eliquid and stash it somewhere (small mixing bottle, back in the juice, although personally I wouldn't try that approach although maybe keep it in a tiny bottle near your actual bottle because there is probably nothing WRONG with the juice but it has been vaped and heated and I'm not so sure I'd want to squirt that back into my large (as yet virgin) bottle of juice, but it's an OPTION etc.
Anna