What's best for your scenario is based entirely on your environment and preferences.
As for whether the ConfigMgr agent requires a reboot, no, not ever. However, some prerequisite components on the agent that are installed by ccmsetup (the client installer) may require a reboot; e.g., .NET Framework if that's not up to date. Even if this is the case though, ccmsetup won't ever initiate a reboot. It'll simply stop and happily wait for some other event to initiate the reboot after which it'll pick up and finish the installation.
Also, just because you have a requirement to only reboot once, doesn't meet you can meet this requirement based on what you are doing and how you are doing it.