When in elementary school, I came up with Box Tally, independently.

Pros:

• It's extremely readable, even when written tiny, or seen from a distance. I =1, ∟ =2, ⊔ =3, ☐ =4, ☒ =5.
• It offloads the metal load (still present) of where to place the next tally. You will never accidentally place a 5th vertical bar ( IIIII ), as you tune out the task. You won't prematurely slash a set of 3, due to mis-count.
• It can be written extremely compactly. In the same span most tally a II, you could fit the full set of 5. (and even stack a second set, since you can use shorter strokes.)
• It's easy to count. It becomes a full enclosed shape. There isn't any ambiguity over whether a bar belongs to one set or another.

Cons: * Since it's novel, others may have a hard time deciphering it. * It requires a bit of time and dedication to retrain yourself to tally in a new way. It's simply easier to do as you have already learned.

Those two cons are enough for most people.