Not necessarily, but it won't hurt to do so. Most dwell problems are caused by worn distributor cam lobes and/or bad shaft bushings, but the dwell does not change much like it does on a Ford distributor. On Fords, the single point pivot system at the breaker plate results in a slight dwell change as the vacuum advance moves. Not so on GM distributors.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!