Foot orthotics or supports are supposed to correct biomechanical problems of the foot and to improve the biomechanics of the feet. There are many different types of foot orthoses and methods of making them for clincians to use and select from. A lot of people require and do reap the benefits of made to order foot orthoses while others will be helped by the easier and cheaper mass-produced foot supports. Which one is best for each individual depends on what exactly is causing the problems and what the treating podiatrist recommends is the best for that person. Many different foot orthotics include diverse design characteristics and a good clinician will attempt and match those up to the needs of the individual. If this is not done correctly, then there might not be any kind of improvement in the symptoms.
Foot orthoses aren't without their issues. When they are not the right one for the individual, then they won't help. You are also constrained by what footwear you need to use, in that you need to be able to fit them into the shoe and there may not be enough space. There are also kinds of footwear, like the flip flops that they simply can not be used in. This could present an issue in warmer places that make closed in shoes necessary for foot orthotics uncomfortable. There are options, for instance, the Archies that have a foot support built in. The shape of the arch supports in these sandals resemble what you should get in an over-the-counter arch support, but probably not as good as what you would get from a custom made foot orthotic. Using these do give you a practical option to foot orthotics, depending on where you can wear them and the character of the biomechanical problem. If you do require foot orthotics there isn't any harm in trying these types of alternatives or raising it with your treating clinician to determine what they believe.