Friends list nickname editing limit (~20/day?)

This is probably not very interesting, but I was just classifying friends in PoGo (tagging with region and gift activity). Got following message whilst changing friend nicknames:

»You've changed nicknames as many times as you can for now.«

So presumably there's a daily limit on that. And haven't seen this particular constraint documented anywhere.

• Now I seee 17 friends with nicknames (just started).
• While 17 is the best of all prime numbers of course; it would be a strange limit here.
• Let's assume ~20, since I likely edited a few more than once.

Anyway, this will likely answer itself by tomorrow. But is the assumed ~20 friend nickname changes (or edits?) the cap per day?

So after some testing, my conclusion is that it's not a daily cap.

• You can have 20 friend nickname edits every 2 hours.

• It's really every edit and not just effective changes. (Every save counts.)

Based on what I have tried and tested is 20 friend nickname changes per hour. It has worked consistently each time by starting 5 minutes after the hour and finishing by 15 minutes until the next hour. Sometimes you can end closer to the hour there were times that I finished by 5 minutes until the hour and it would allow me to change the next 20 a minute or two past the hour, and other times it made me wait until the next hour. it is all about timing, your time versus the game time. I have noticed that Ex-Raid times are off which has to do with server time deviation.