There probably is no point checking someone's Instagram following list every few hours, but waiting too long could mean missing smaller changes. I am trying to figure out what would be a reasonable frequency for monitoring a public account. Once a week might be enough for casual interest, while someone tracking an account closely may want more frequent checks. How often do you think Instagram following activity should be checked to notice meaningful changes?
Sometimes I get annoyed by Instagram's unclear display of recent followers. I remember one time I had nothing better to do and decided to look for a way around it. That's when I started seeing who instagram follower tracker (https://recently-followed.com/) me specifically. It made using Instagram so much easier. Even though you have to use another tool, it's all so fast and efficient that it's like you never left the app.