I clean them when they need it. No particular round count. Sometimes one of the plinkers may see over 1,000 rounds before its cleaned. My match versions will be carefully stripped, cleaned and lubed after every session. It boils down to the particular rifle and its role. The one hole groupers are treated as such and the truck bangers are shot till they start getting hinky. I do not use steel case ammo, bi-metal bullets, or any import ammo. Most of what I shoot are handloads with known very clean burning powder. Thus I can get a lot of rounds through one before it acts goofy.
Slightly off topic: I did an experiment on a box stock stainless 10/22 recently. Took it out of box new, ran a brush down the bore, lubed it, fouled it with one magazine and fired three 5 shot groups off a rest of Federal Premium Match at 25 yards. Then sent 7,500 rounds of mixed brands and types without cleaning the rifle at all. At the end of the cycle I fired three more 25 yard groups off he rest again with Federal Premium Match. I completely disassembled the rifle, cleaned it meticulously, fired one magazine to foul the bore then fired three more 5 shot groups at 25 yards under same conditions. With this bone stock rifle the difference between 7,500 rounds dirty and clean as a whistle was discernible but negligible. The worst set of groups were the first set when it was new. Now it is ready to be stripped and built into a tack driver. Figured might as well see if I could break it before I rebuilt it. Tough little rifles.