A few additional comments:
As one can see from the range of comments, there are a wide range of foot problems and superfeet offer one set potential solutions. If they work for you and your feet--great! If not, try something else. And if your problems are sufficiently "interesting", you may need custom insoles.
I have had several sets of (rather expensive) custom insoles. (Even the pros don't always get them right--ultimately one has to try them to see if they work.) One thing I did get from the custom insoles (at least from the pair that worked...
) is a knowledge of what kind of support I needed. The custom insoles gave some support that the green superfeet didn't, but the superfeet are good enough to fix my problems (and a lot cheaper...).
And yes, superfeet flatten with time. But appropriate support is appropriate regardless of the age of the insole. If new ones work and continue to work as they age, fine. If not, then replace them as needed. (Of course, it is also possible that old ones will work better than new one...)
Ultimately, you just have to use trial and error to find the right ones.
One also needs to consider the shoes as well as the insoles. None of the insoles can support your feet on its own--they all pass the forces on to the sole of the shoe. The support from a shoe can break down before the shoe looks worn. (I understand that this commonly happens with running shoes and serious runners have to retire their shoes before they look worn. And, of course, many modern hiking boots are being built on running shoe technology.) So don't forget to consider the entire system--changing the boots might also help. (And if you buy new boots, fit the boots with your chosen insoles.)
BTW, the very soft insoles (often found in drug stores) are pretty useless, IMO. The softness may feel good in a finger test, but think of the underfoot pressures when you walk or hike--hundreds of lbs/sq in. This will crush soft sponge rubber into nothing. (And the constant pressure from the soft insoles can prevent blood circulation in the soles of your feet.) A firm insole will give a much more stable platform for your feet.
Good luck with it...
Doug