Hi @czw_x, I guess you've already read the docs. Windows devices syn approximately every 8 hours.
Q: What is it that you want to speed up? Are you're policies not applying as quickly as you want or expect? Is it app installation?
There are different actions that trigger a sync. One is when devices receive a notification from Intune to sync, another is a scheduled sync. This might be what you're looking for, although I wouldn't recommend changing this if you can live with the defaults. If you do decide to change the default sync interval, I suggest you test it first and understand what's happening under the hood.
When you enroll a device, 3scheduled tasks will be created and enabled to run on different schedules. Have a look at Scheduled task #3. This one will run every 8 hours. It will run the program deviceenroller. (%windir%\system32\deviceenroller.exe /o “{enrollmentId}” /c /b) to check-in with Intune and start a sync.
Hope this helps.