Hello all. First post on the forum

Sometimes I spin the handle and engage the thumb bar right after to test out the free spool time of my baitcaster. Could this be damaging to the gears inside? I've seen some youtubers do it, that's where I got it from.
 

Thanks

Yes its bad. The thumb bar could not stay open at times when you let go of it and then cause the gears to  engage/grind while spinning at speed this lead to very rough gears. 

Disengage the spool and spin it with your finger to test your freespool time if you really need to.