I have this question too. What is best practice to keep the iPhone optimized? Do I have to sync the iPhone with my Mac and allow the Analytics&Improvements to collect the logs?

Analytics are just rouble reports that are sent back to Apple and describe the OS events leading up to a crash or other failure. Whether you share those or not will have no effect on the optimization of the iPhone.

Likewise, syncing the iPhone to you Mac isn't necessarily a must-do thing.

Generally speaking, the best practice to keep the iPhone optimized is simply to keep the iOS updated as Apple sends out new versions. And reboot the iPhone from time to time, maybe once a week.

What apps can I use your iCloud