Sounds like this is this a large cartridge fuse intended for main disconnects, which is not the correct type fusebox for household circuits. But no don't overfuse; that is not safe & if you had a fire then your insurance might likely be voided. I believe for that you need the screw-in base Edison type fuses available in 20A size, etc. That is a Buss W20. The thread looks just like a light bulb's. Buss sells them in plastic housing now (no more ceramics) although 30 amp W30's are still available in ceramic.
The larger cartridge fuses may be available in a 20 amps version but I'm not sure about that. Try asking at an electrical supply warehouse.
The larger cartridge fuses may be available in a 20 amps version but I'm not sure about that. Try asking at an electrical supply warehouse.