This is one of those things where better components make a difference. If are able to anticipate your shifts, any component group will work. This is easier said than done sometimes, and more expensive components seem to handle this better than cheaper ones do. It is one of the reasons why they are more expensive.
That said, venerable bar end shifters may make a difference. If your derailleurs can shift, then these bad boys can shift them. You have not said what kind of bike and more importantly, what you have for shifters and derailleurs.
As the previous post said, although I will word it differently, the best thing you can do is anticipate your shifts. If things are so screwed up that you have to stand on the pedals to make them barely crank, no shifter on the planet can deal with that much force and pressure.
I might disagree slightly with John's climbing strategy, but it is only in the name of diversity.
Once again there are two kinds of people on this planet: mashers and spinners. John is a masher, and I am a spinner. I never get out of the saddle, except to get off the bike. I maintain a pedal cadence (fancy word for revolutions per minute) of 80 to 90. Always. When I drift above 90 I up shift and when I drift below 80 I down shift. I have mountain bike components (including a compact drive front crank) as this favors being a spinner. My touring partner is a masher and it works for him.
Either strategy works, and you can decide which one you want to be.