How fast does the traffic load of WiFi network change? What is the average time that the WiFi traffic load remains constant for different traffic types e.g. internet browsing, video streaming, voice call, e.t.c ?
Your question is not highly dependent and specific on wifi. It seems more important to think in terms of network traffic.
If the WiFi hub considered serves a home, you need to build scenarios:
-family members: children, parents, flat sharing people
-working hours: if working from home, how many videoconferencing sessions ,average duration, data upload and download between home location and organisation VPN
-outside of working hours: sessions of gaming, movies ("Netflix" or equivalent, movie of 120 minutes or more etc), music streaming. Browsing, YouTube, etc...
You may run a number of differently populated scenarios to explore and understand...
This may show you the limit of WiFi and take you into fine access...
As to how to picture for yourself what happens in homes during the current era of Covid19, you may benefit from browsing this study/model:
In fact, one interesting little factoid is that in the US, where many people were already streaming video at home, long before the pandemic, the ISPs themselves did not have major problems, supporting the traffic increase caused by telecommuting. The patterns of traffic shifted, more b/s to homes during the day, for telecommuters, but the capacity to homes already existed. Streaming video, especially in high resolution, requires so much bandwidth, that backhaul network capacity to support home WiFi was not so much an issue. At least, in urban and suburban locations.
The problems had more to do with the remote authentication server and firewall capacity, of individual businesses, as most of the workforce started working from home. Easier to solve, than it would have been to upgrade all those ISP networks throughout neighborhoods.