NoChecking valves is not a waste of time or money.
That said, if I'm correct, the FZ has valves clearance set with shims of a certain thickness, and this kind of technology makes that valve clearance is much more stable in time than with other more traditional screw/counter screw adjustment.
I suppose that's what your mechanic meant.

The drawback with shims is that there's much more work involved if any adjustment is required.
1. You need to go to your dealer and buy (order?) the shim(s) of correct thickness after you measured the clearance.
2. You need to lift the camshaft to replace the shim underneath.

Screw/counter screw clearance is not as stable as shims, but if adjustment is required then that only involves a bit of screwing, as the name implies. In particular you don't need to visit your dealer.

So there's good and bad with both options.

True, but I found it shockingly hard to find a mechanic that would check my valves for me - most outright refused saying that if the bike started then everything is fine. This was both in my home country (UK) and all the way across Asia. I finally found someone who both had feeler gauges and was willing to check in Kathmandu, but then they didn't have shims for a Suzuki (I had a DRZ, which has shims instead of screws like the DR), so I ended up having to ride with valves out of spec all the way from Nepal back home to the UK. I haven't had a chance to crack open the bike because it's hard to find a workshop in London, but I suspect I've sustained some damage.

I mean, it is impressive that the bike managed to keep going despite this, but it kind of goes to show how problems can start to compound themselves when you can't do stuff yourself. I'm considering buying a DR in the States for my next trip, but ONLY after I've taken apart my DRZ and rebuilt it and feel confident. I'd honestly never reccomend someone do what I did (that is to say, taking a used DR/DRZ, no preventative maintenance done (cause I couldn't find someone in the UK to do it for me), and then take it on a big trip. Too many mechanics either didn't have the tools, wouldn't work on my bike, couldn't communicate with me, or weren't very good, and I spent SO MUCH time chasing problems wondering whether the last mechanic put the carb back together properly or knew what he was talking about when he said something was fine. If I hadn't been an idiot mechanically I would have fixed it quickly, moved on, and not even given it a second thought and probably be posting here about how reliable the bikes are

Note: a lot of these problems seem greatly lessened in the Americas.

Realistically I don't think it's very hard for ANYONE to get to the point where they can do this stuff on a DR/DRZ (We'll certainly see when I finally get a workspace) but not everyone has the opportunity to do so.

I don't know about the DRZ but on the DR650, if you're to the point where you change your own tires, fork seals and wheel bearings, this bike is easy to keep in top condition. Checking/setting valves is not difficult, it just takes a while to figure out how to get your hands in there.

I would do a complete service on the bike before leaving home, just to figure out which tools I need to carry with me- as well as have a little familiarity with the bike.

.............shu