do small changes to maps require massive sync time?

Android: I created some maps, ~100 000 tiles. Next day, noticed that one of them was duplicated. Went here

https://www.gaiagps.com/datasummary/maps/

and deleted one of the dupes.

Next time I started Gaia on the phone, it stayed busy for over an hour, saying that it is "fetching changes". Still going, so I don't know how long that will take.

If all these maps are really not separate maps, but are combined into one Gaia data file, does that mean that a whole new data file must be synced? I thought that my updates were faster in the past, and that the only thing that is slow is downloading a large map file. Seemed like it took about an hour per file.

I have the phone powered so that the battery won't die, and letting it run to see how long it takes to process deleting a map file.

edit 20190418a: I have 2 items to update,

1. After many hours, I checked my phone and tablet.They both were powered off. I don't mean just off, I mean powered off. Dunno why.

2. So I deleted the accounts on both devices, reinstalled them, moved storage to SD cards (my cards far exceed the posted recommendations), and resynced the maps.

Here is the interesting point. The first bunch of maps on my phone downloaded so quickly that I had to double check that they were, in fact, downloaded. Then we started loading the router. We work from home, and keep regular hours. As soon as we logged into our VPN and started to work, the download speed for the maps slowed to a crawl. The only way to test this again is to repeat the steps when we don't plan to load the router. If this observation holds, it means that GaiaGPS download speeds are quite acceptable. I'll try to test this on the weekend, and update this.