The garbage bin...I'm not wasting storage space keeping a few grams of material, nor am I wasting time on useless models that I'll eventually throw out anyway.
I've had tailouts catch in the reverse Bowden tube a few times, I'll run as far as I can and then scrap the remainder, can cause issues even with one of those encoder filament sensors. I do try to collect it, want to start recycling material myself at some point.
Im using a filament fuser 3d printed. Try looking for filament fuser/welder/connector on thingi or any other page. There are also professional solutions on the market but diy cheap printed thing works flawlessly for me.
I save all of my end of life spools for prints that I'm going to be on hand to supervise, then just spend the day hopping up to swap filaments every half hour or so as each one runs out.
Sometimes I use the 'crumbs' for a small print, like model bases or tests. Other times I weld all the remainder together and run it like normal. (This works for me because I tend to print in the same color and material alot.) My other option is using these small amounts for my 3D pen, which I use to join parts together like a welder. It works really well for some of the dice towers I print that come as two or three parts, on seams that won't show. I super glue the last joint so everything is solid and seamless to the eye.
Depends on lots of things, but I'll either feed it through in real time to an ongoing print until it gets in the boden tube, or for my direct drive, it's got it's own run out sensor so I'll use it there and just join it up.
If it's a one off filament that I don't have more of and don't plan to restock, I just use it for bed leveling tests and the like, or on prototype prints that can have multiple filaments. For ones that I have more of, I just keep an eye on the printer when it's running low, and shove the new filament in as the old one runs out. I don't even bother with a runout sensor or pausing the print, I just let the old one fuse with the new inside the extruder and call it a day
Simple - I don't worry about it at all, I just load up a second spool of compatible material and let the printer switch when the first spool runs out (X1C with AMS).