Foot orthoses or supports are designed to improve biomechanical abnormalities of the feet and to improve the biomechanics of the feet. There are lots of various kinds of foot orthotics and techniques of fabricating them for podiatrists to use and select from. Many people need and do benefit from custom made foot orthoses while some will be helped by the easier and cheaper mass-produced foot supports. Which one is the best for each person would be determined by exactly what is causing the problems and just what the treating specialist recommends is right for that person. Many different foot orthoses have got different design characteristics and a good clinician will attempt and match those up to the requirements of the individual. If that is not done the right way, then there may not be any kind of improvement in the symptoms.
Foot orthoses are certainly not without their issues. When they are not the right choice for the individual, they'll likely will not work. You are also restricted by what shoes you need to use, in that you have to be able to fit them into the footwear and there may not be sufficient space. There are also types of footwear, for example the flip flops which they simply can not be used in. This tends to pose a problem in warmer climates that make closed in shoes necessary for foot orthotics uncomfortable. There are options, for instance, the Archies which have a foot support built in. The shape of the arch supports in these flip-flops are similar to what you will get in an over-the-counter arch support, but most likely not as good as what you would get from a custom made foot support. Using these do provide a helpful replacement for foot supports, based on where one can wear them and the nature of the biomechanical problem. If you do need to have foot orthotics there isn't any harm in trying these types of options or raising it with your treating podiatrist to determine what they think.