only tubulars need to be stretched, inflated and seasoned
if the rider believes they are more supple (they are)

beaded tires can benefit from being mounted then run on a drum overnight with
an electric motor to add suppleness.

a racer usually does better when the tires have brand new tread but the sidewalls have
been worked or flexed as though it has been used for a few hundred miles.

this is the .00001% advantage. in other words, it is fine if you don't it is fine if you do. YMMV