Many people use custom orthotics or aftermarket insoles. In hybrid racing, where one shoe does many jobs, they can change how a shoe performs.
This is general information. If you have been prescribed orthotics, follow the advice of the professional who prescribed them.
Fit
Orthotics and insoles take up space. A shoe that fits well with its original insole may feel tight with an orthotic. Try shoes with your orthotics in.
Remove the original insole
Usually, you replace the original insole rather than adding on top of it.
Stability
A high insole raises your foot in the shoe, which can reduce stability and increase heel slip. Check this on wall balls and lunges.
Heel slip
If your heel lifts with an orthotic, try a heel-lock lacing method. See lacing techniques.
Multiple pairs
If you use two pairs, you may need to move orthotics between them, or have a second set.
Breaking in
Break in any new insoles or orthotics well before a race. See breaking in race-day shoes.
Do you need them?
If you do not have a specific problem or prescription, the shoe’s own insole is usually fine.