Why would you want to? Well, because you moving a whole lot of repetitive development from individual forms to a reusable class where it is shared by all your forms.
What can I do with Sub Classes? Things like
Enabling Save and Undo buttons when you edit (dirty) a form, disabling those buttons when you undo or save the record.
Using a sub class for your command buttons to do the Save and Undo
Using a sub class for your combo and text boxes to highlight the current control without using Conditional Formatting. Using this technique allows you to set a background colour for either locked or unlocked and allows you to change those On Focus background colours in just one place.
Have a look at this simple example and download the demo app from the link below.
Then join me and a bunch of other Access Developers on January 4, 2024 at the Access User Group Pacific chapter for a more in depth demonstraion.