As with many things in Dynamics CRM Development, there are more than one way to do the same task. Take the addition of an OnChange event handler, for instance.
Well, it honestly depends on the number of OnChange events you have. Let's take the Contact, for instance.
Is there a huge difference? Not really, but the code-route may be a little faster and easier to maintain than having to edit the properties of each individual field. Since all of my phone field OnChange events are right in front of me, I can easily see which have events attached.
Does technique #2 work in all cases?