Foot orthotics or supports are built to improve biomechanical issues of the feet and to help the biomechanics of the foot. There are many various kinds of foot orthotics and techniques of fabricating them for doctors to use and choose from. Many people need and do benefit from custom made foot orthoses while some might be helped by the easier and less expensive mass-produced foot supports. What type is right for each individual would be determined by what exactly is leading to the problems and just what the treating clinician suggests is right for that person. Many different foot orthotics include diverse design features and a good doctor will try and match those up to the needs of the individual. If that is not done the right way, then there may not be any kind of improvement in the problem.
Foot orthoses are certainly not without their issues. If they are not the correct one for the individual, chances are they will not help. You are also restricted by what shoes you can use, in that you have to be able to fit them into the footwear and there might not be adequate space. There are also varieties of shoes, just like the flip flops which they just can not be used in. This could pose a challenge in warmer climates that make closed in footwear required for foot orthotics uncomfortable. You can find alternatives, for instance, the Archies which have a foot support built in. The shape of the arch supports in these flip flops are like what you would get in an over-the-counter arch support, but most likely not as good as what you would get from a customized foot support. Using these do give a practical option to foot supports, depending on where you can wear them and the character of the biomechanical problem. If you do need to have foot orthoses there is no harm in trying these types of alternatives or raising it with your treating clinician to determine what they think.