(As usual, I did search, but maybe this exists and I simply am too dense to see it. In that case, just point me in the right direction please.)
Currently, Tinkercad remembers everything you've done to an object - which can be great, but also means that whenever you load up an object, every single step of manipulation is backtracked.
Admittedly, I'm a rather sloppy worker - I take something that is close to what I need, adjust it, then copy that result a thousand times and apply it where wanted (further modifying it, grouping it, etc...).
The clean way would have been to take the modified object, download and upload it, and use this as the base of the rest. But that takes time I usually don't want to spend.
The result is that when I open a complex design, I'm greeted with hundreds of kludgy "hole" blocks removing unwanted parts in a dozen locations, just because the original gear (for example) wasn't alone and I only needed a single gear.
So it would be nice if there were a way to tell Tinkercad: "Forget any history this object might have and treat it as if it were uploaded in that state!".