So do the different checkboxes each have completely different code in their callback functions? Like you have 20 totally different codes? Or all 20 checkboxes do the same thing, like gray out a label or disable a button or something? Also, what function is calling those 20 callbacks? Are the callbacks of checkboxes 1, 2, and 3 all going to check the values of checkboxes 75 through 87 and execute the callbacks of whichever were checked?
Why not just have one function, called ProcessAllCheckboxes(handles) or something and in there do stuff?
function handles = ProcessAllCheckboxes(handles)
The "something" could be the same single function, or it could be totally different code. Each checkbox's callback could simply call this same function, for example, for checkbox1:
function checkbox1_Callback(hObject, eventdata, handles)
handles = ProcessAllCheckboxes(handles)