Typically... No

Provided your equipment is in good shape, you should not experience any brown outs... a pro would more than likely replace a faulty piece of equipment than to rely on a glitch buster. Modern brushless servos tend to run far more efficiently and are less likely to cause brownouts plus modern ESC's come with stronger BEC's as well.

Glitch busters and UBEC's used to be necessary if you ran a combination of an older Savox servo (notoriously drew high power) with an older Spektrum radio (notoriously weak signal problems) with an older Castle Creations ESC (notoriously weak BEC's) as an example. Modern versions of these brands of products have since corrected each of their respective deficiencies, though I caution that Savox still sells some older high drain technology, which will should perfectly fine provided you are using an ESC with a BEC of 3A or higher in most cases.