Yeah, I either do it for hours on end or ignore my 3DS for several hours. It's better to plot reset while doing something else, such as watching something on Netflix.
I don't lose my cool while plot resetting by not having a very specific spot in mind, I tend to have a general area or areas where I want that villager to move and as long as it's not a terrible spot or on top of something, it's done. Of course, that's probably tougher if you're more selective about it. I guess you could try to take a lot of breaks and do something else like listening to music or watching TV while you're plot resetting, as long as you don't pick the wrong options on the start screen.
Distract yourself with something else while you do it! Distraction is key. I either have music on that I can sing along to in order to let out some of my rising energy and frustration, or have a TV show or movie running that I can watch or listen to in the background. There's also the Pomodoro method where you plot reset for, say, 30 minutes, then break for 10 minutes, try again for another 30, etc. Taking breaks and spreading it out can help immensely.
I don't have the patient to plot reset for too long... Recently Deirdre moved in and thank gods that the second time, the spot she chose wasn't too ridiculous. I usually just go 'meh, good enough.' If they don't destroy my hybrid breeding patches, that's good enough for me.
maybe you already know or im dumb or its a rumor but if they keep going into the same spots when you reset, try fully shutting off your ds then retry and they should spawn in different areas I think.. Sorry!~ If not just try to take breaks, dont be as specific, and be flixible with your paths and stuff