Correct, there's no advantage to going over 100%.
Also one thing I want to be sure we're on the same page about - when I (and others) recommend you take items to level 16, especially early on, please please please be diligant about the items you choose to take to 16.
In all cases, never waste silver on a 3* item or lower. More than likely you shouldn't even bother with 4* items - 5* should be the minimum. Never waste time with common or uncommon items. Ever. Even 6* ones. Sell them instantly.
With the remaining items, upgrade just to level 4. If it's a rare item and the level 4 upgrade didn't hit a good stat (see below for more details on that), sell it. If it's an epic or legendary item and the neither the level 4 nor level 8 upgrades hit a good stat, sell it.
What that should leave you with level 8 items with at least one good substat upgraded. Next, go to level 12. For rare items, if the level 12 upgrade didn't give a good substat, sell it, or archive it for use later on champs that don't need super good items. For epic and legendary ones, do the same if the level 12 upgrade didn't upgrade a good stat.
Finally, if the level 12 upgrade was good, and it's a glove/chest/boot/ring/amulet/banner, take it to 16. If it's a weapon, take it to 16 if your champ is ATK based. If it's a helm, take it to 16 if your champ is HP based. If it's a shield, take it to 16 if your champ is DEF based.
What's a good stat, you ask? All of the % based stats for your champ's primary stat (ATK% for ATK champs, HP% for HP champs, DEF% for DEF champs), as well as ACC, SPD, CRATE, and CDMG. RES is very situational - for your stage of progression I would not consider it useful. All of the flat primary stats are useless.
One of the absolute biggest mistakes you can make in this game is spending silver upgrading bad items, especially if you take them to level 16. It can cost enormous amounts of silver to do that, and especially early, silver isn't a luxury you have.
A final note - as with everything else, I highly recommend you only upgrade items during artifact enhancement events. I would even argue you shouldn't bother with just any event - you should save your silver for artifact enhancement events that occur during fusion/fragments. That way you get triple the bang for your buck - you get the upgraded artifacts, as well as rewards for the event, and even better, you also get fragments or champions for the fusion.