bike wrench

I'll thrown in another perspective, because I dont think they solution is that you just need a more expensive bike. Obviously, you can work on adjusting it better like others have noted, but also keep in mind that you are probably likely to have trouble any time you are cross-chaining. People tend to like to just change gears on 1 shifter, but you do need to be using both to keep the chain as parallel as possible to the bike. Also, while it's sometimes unavoidable, avoid shifting under large loads. If I'm pedaling hard, and I need to shift, I might up my cadence for a few strokes, and then shift while pedaling slower so there's not any load on the chain.

Personally, I think indexed shifters shouldn't be seen as the "default" as much as they are. I have a bike with a modern friction shifter with 1x10 gearing, and I can shift from 1 to 10 with a single motion. Even on my 40+ year old bike with friction shifters and 2x6, it's pretty easy cause all you do is move the shifter till the bike shifts and noise stops. It's slower, but that only matters if you are racing or doing fairly dynamic mountain biking. For the average Joe, it's fine. With my modern bike, I can shift faster than anyone.