My experience so far is that early on im doing thinks about every 10 minutes and thats just because I am giving continous short exration routes to my probes and getting some basic stuff running. But that is probably only for the first hour. After that I check in once an hour to two hours to check on my probes and get my initial mining setup. Thats the first day after that then its easily ten minutes and then waiting for certain things to happen which can take several hours.

As for combat I couldn't say. I havent experienced any yet.