Yoyo Bag

The second yoyo cannot land on a target the first one just hit, because the whole class shares a single invincibility timer. Against a lone boss the extra yoyo is mostly decoration. This is the most misread accessory in the class and the reason people call the bag overrated after testing it on a dummy.

Worms and crowds are the opposite story. Every segment counts separately, so two yoyos and two counterweights bouncing around a Destroyer or an invasion wave can multiply your output several times over. If you plan to run yoyos in hardmode at all, that is the fight this exists for.

Longer string sounds minor and is not. Yoyos live or die on whether you can hit something without standing in front of it, and the extra reach lets you hold a lane you could not hold before. The counterweights orbiting you also swat small enemies and projectiles off your face, which is real defense you did not pay a slot for.

While the second yoyo is out your spin timer drains much faster, so you are re throwing more often than you would bare handed. The bonus duration built in covers some of that but not all of it. Nothing else in the yoyo accessory family stacks with this, so once it is equipped that decision is made.