Usually, the most problems will come from the high beam multifunction switch. If it hardly ever is used, sometimes the factory applied grease in the contacts will dry up and cause connection problems. Sometimes similar problems occur with the hazard switch function, once you need it, it doesn't work unless you actuate it a bunch of times to cut through the dried up grease.

I've sucessfully taken the switches apart on some vehicles and cleaned out the old grease and Scotchbrite-ed the contacts, and reassembled them with new grease.