I tried to keep up with ACNH and ACNL daily for a couple of months, but eventually got overwhelmed and started to fall behind on ACNL back in late June. A couple of days ago, though, I dove back in and had a great time, so I think I’d like to continue balancing both games.
I’m working on this formal garden in one of my ACNL towns, and it isn’t quite finished yet. I’ve found that having a specific goal in mind for each game makes it easier to keep up with the different towns.
As for older games, I returned to the GCN game repeatedly over the years, across four or five towns. My GCN clock battery isn’t working right now, though, and I’m not sure what that would mean for AC. I came back to WW and CF a little bit later on, though not too much (in WW, one of my favorite villagers moved, and in CF, grasswear caused too much stress).
In terms of returning to ACNL, and concerns voiced above about villagers moving, I have a couple of ideas. First, if you remembered when you paused, go back to that date and play day by day until you stop a mover, and then jump ahead. Secondly, there is an Amiibo reader accessory you can buy that works work older 3DS models. I had trouble finding it on its own, so I bought it bundled with AC: Happy Home Designer, if you don’t already have that. I don’t know what stock is like these days, but it should be available. I used it a number of times without issues, though I eventually upgraded to a N3DSXL for other reasons.