How often do you adjust valves on 850 suzuki c50?

First of all, it's not 850cc, it's 805cc.

You want to adjust your valves when they get noticeably louder or quieter. Louder = loose. Quieter = tight.

Loose is better than tight. Too tight can lead to burnt valves and low compression.

I adjust my valves at the start of every season.