As far as I am concerned, if the valves were adjusted when you said they were, there is no need to check them until 12000, 15000 etc. Valves do not go out of adjustment every 5000 kls, unless there is a problem. Just bought my 94 with 44000 kls & the valves were at the far end of ok. Did not look like it had ever been adjusted before. Depending on your yearly mileage, I wouldn't bother checking them more than every 10,000-15000kls. Just change the oil when it's due. Most important!