I think this varies a lot depending on your system - size, what dosing you run, what type of filter. In my case I run a RSR 250 (65g) with two 250 micron filter mesh socks. They get cleaned weekly but could easily last longer. We are about to go on a cruise for 13 days and I will clean them the day before we go and the day we get back - don’t expect any issues. I currently dose AF 3 part 24x7 but nothing else - no reactors, no GFO, no carbon, no UV.
When I ran NoPoX earlier I found the socks didn’t last as long, as I have seen others comment you tend to get a bit of a slime buildup, no doubt due to the extra bacteria consuming the carbon. Even then however my socks lasted a week - by the end of the week however the first sock was overflowing pretty much 100% to the second sock.
Even when I run 100 micron socks occasionally I have no issues getting a week out of them, would probably also last at least 2 if I needed. This is just how my tank behaves, yours may be different.