The only thing that isn't instantaneous is the recalc - as soon as you click on a checkbox, it changes state. And, if it's a form with multiple checkboxes, I'd have thought the only time the recalc issue might matter is when the last checkbox is checked. Quite obviously, you need to ensure that one gets exited.

Whether you're using
a) Forms Protection; or
b) Editing restrictions; or
c) no restrictions,
nothing happens until you exit the checkbox.

No, you don't need an on-entry macro. Rather, the on-exit one can handle the re-selection. That will trigger the on-entry macro of its own accord. BUT... Visualize this -
1. Select Checkbox
Do While not tired
2. Exit Checkbox
3. Macro kicks in
4. Checkbox re-selected
Loop
No, but I do know it's old technology that MS moved away from long ago. It's probably only being retained for backwards compatibility and may be deprecated in another version or two.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]