Assume a scenario where you can multiple projects under each course object. There is a nested object creation form like the one below
Given the maximum limit of 5 Projects. Which is a better scenario ?
Option A: Disable Add after 5 Projects are added. Option B: Do not prevent adding a new project and but show error on 'SAVE' if exceeded. [But highlight the MAX: 5 in bold red (or some visual way) when projects are being added beyond the limit].
The advantage of Option B is that, if the user wants to replace a project he has the option to add new and then delete, rather than forcing him to delete before adding. The advantage of Object A is that error is preemptively prevented, but with a trade-off of a little flexibility.
Thoughts ? Suggestions ? Which is better Option A or B ? Or is there a better way to do this ?