I am not sure if there is a wrong or right way. Both of them have their advantages, both of them their weaknesses.
The company I am working for also modifies LDAP schema files from time to time, but not as regularly as in your case. We are also having the same dc for both the devel and production environment. At our company, there is no chance that we might mix up something since we are only changing a schema from time to time.
Your new company might have different views than you, and they even might have some sort of policy for devel stuff. My advice would be to write down a little concept where you compare both ways. If you still think that your "solution" is the better one and more effective, you should be defending it in front of your supervisor. Maybe you can convince them to switch to a new policy. But do not forget to respect their current policy and do not be too offensive. Keep in mind that you might be walking into something that has not been changing for years, and some people are afraid of new things (sadly especially in the IT sector).
Writing a concept is by the way my most successful method to convince customers or even people at my company. They see that you have done some research and that you have arguments. When they are valid, you will walk the successful path!