I consider myself an adequate quilter. As in everything, there are many different answers depending on your style, your desires, and your equipment and/or budget. So for me, it is more about functionality of keeping everything together while on the bed or in the wash. I can do pretty sophisticated designs on a long arm that I can't approach on my sit down machines, but some people can do marvelous things on a featherweight!
If I can run a design off the edge I will. In designs where I can't, I overlap a few stitches, or you can stitch in place/use a machine setting to tack, then I pull the top thread to the back and being careful cut both ends close.
I've found in all machines I've had that I really have to cut the threads when I move from one place to another, just leaving the thread whole is asking for trouble for me but if I have problems cutting where it is, I switch to a basting mode to move positions, again tacking my start/stop points, and then remove the basting stitches when I'm pulling down my tails. Other people/other machines have other issues or other solutions.
We have some truly great and inspired quilters on this board. It's amazing how they can enhance a nothing top by their stitching, and elevate a great top into a masterpiece. It is a skill set and a design eye I don't have -- but I'll watch this thread for pointers!