Yes, your chain is probably longer than need be to allow big-big so you may be able to shorten it a bit.

BTW it's not rumor, it's proper technique. Loop the chain over big-big without going through the rear derailleur. Overlap the ends and add 1" (two half links) and make the chain that length. Be sure the ends are a proper match (inner/ outer if using a joining pin, two inner links if using a master link). If you come up between links, go to the next longer pin. Then route the chain properly and join the ends.

Slack in small-small isn't a major problem as you should never use that combination and it's just a nuisance if you do, not damaging despite warnings to the contrary.