Often a fuse which fails, has been subjected to high current due to a short to earth (chassis) on one of the circuits it supplies.
How can you fault find in this situation? Just replacing fuses can be costly and vague as to which part of the car's circuit caused the next fuse to blow.
Try connecting a standard car trouble light which runs off the cars battery, in place of the fuse. You can remove the alligator-clips, bare the wires, twist or solder the ends so they are rigid. Then push each wire-end into the clasps which receive the two fuse spade-terminals. This in effect is placing a current limiting load which will light in the event the short re-appears. In most cases, you will not be able to drive the car if the circuit powers essential facilities such as lights, ignition etc.
When you are ready to fault-find, preparing to wiggle wiring looms to look for the intermittant, place the lamp in plain sight, so you can see if it comes on (indicating the short has come back) as you investigate. This will require leads of about 10 ' or more.
Note, this test will not cause any wiring damage, as the lamp limits the current to about 1.5A.
Jason