The fuses for my turn signal burn out, but only during winter months when the temperature gets below 40 F.
I’ve increased the fuse rating from 15 to 20 amps, but no change. I don’t want to push it any further than that, though.
You NEVER install a fuse with a higher amp rating than what the circuit requires. That is unless you don’t mind replacing all the burnt up wiring in that circuit.
The problem might be in the multi-function switch in the steering column.
Tester
I would also check bulb sockets to see if any of the contacts are touching.