I have 5 scenarios where I want to send a triggered email. Each scenario has 1 unique variable that will be dynamically populated. Would it be problematic to create one data extension that has the 5 necessary fields and attach that data extension to each of the 5 triggered send definitions? I’d make each field nullable. The developer responsible for the upstream process that generates the values for the 5 variables is doing it in a manner that makes me think I need to take this approach.
Yes, you can use the same data extension for multiple triggered send definitions. There is no issue.
Just make sure that the subscriber key is unique from the upstream for all the scenarios. If the subscriber key is same, then the email address is overwritten in all subscribers with the latest email address.
Also if your triggered send data extension contains a primary key, make sure it is unique across all scenarios, otherwise the data record is not inserted and no email is sent.