When jot is used beside an array, such as in the expression 1∘+, you never need jot. Instead you could write 1+⊢ (for the monadic case). The benefit in using the former is that ∘ forms a derived function, a single bound "token" - (1∘+), whereas 1+⊢ is three: (1)(+)(⊢). This is usually helpful for removing parentheses - essensitally for working smoothly with APL's evaluation order.

There is another form of jot, f∘g - when jot is beside two functions. This forms a composition which has it's own rules about moving arguments.