How to balance WiFi performance

I have an old AR750S Slate with OpenWrt 25.12.5 firmware. So I'm getting used to the LuCI interface. It clearly points out the the Slate only has 2 WiFi radios (2.4G and 5G) but in the wireless section of the Status -> Overview I see the 5G radio setup to support being an AP for main and guest, and for a client uplink.

Can I assume that radio0 has a total throughput up and down, which I hope is duplex, which means that there will be performance issues if the uplink and AP devices are all banging away. How do folks normal decide what goes on the 2.4 and what goes on the 5G. I'm guess that if the 5G is getting a good signal that it should be the uplink to the internet?