1 band is not much better than 0 bands in that if neighboring WiFi hubs have to use the same band they will interfere with each other continuously and you might get 10% or 5% of the theoretical performance. In fact 3 bands isn't that much better than 1, because you need about 6 bands to implement independent cells with WiFi, though WiFi has never really had enough bands for really comfortable spectrum management.

In wired networks you are usually better off to share 3 units of bandwidth with 3 people because not everybody is using the pipe at once but in wireless networks access control is not so good and I'd rather have 1 band to myself and get 100% performance rather than have 3 bands shared with other people because instead of getting 300% performance I might get 30% after contention.

iPhone 16 and 16 pro promised to support WiFi 7 but tests show speeds comparable to iPhone 15 pro. A hidden limitation which does not use the 320 MHz bandwidth. It is unknown if Apple will ever deliver a fix or update to support it.