Yearly maintenance prevents 90% of problems. Read your owners manual and follow the recommended maintenance schedules. Valve adjustment is just one of many maintenance items that is required after a certain amount of hours (which is listed in your owner's manual) This is no different than...
When we had our VW aircooled shop we used tons of helicoils for spark plugs/exhaust studs. Always a success. Used red loctite when installing. As a shop, we would buy starter kits for what was required and then just ordered extra inserts kits as required. Slowly built up to having all the...