Change IP address or nameserver?

Hi - I'm setting up various accounts on my WHM installation. I have a nameserver configured. However, in many cases my clients have customized their DNS on the registrar level, for example, using outlook or Gsuite for email, or pointing sub-domains to different IP addresses, etc. In a case like this, my instinct is to just change the A NAME record to the IP address of my server, rather than change the nameserver and copy all the custom DNS settings to the new cPanel account. My question: is there and substantial difference between using one method over the other? Or is there a standard practice one way or the other?