Gmail is set to the account of the standard mail application of windows10.
"Gmail sync settings" for the app account is
"When receiving the item" is selected.
(1) If you start the mail application and the window is displayed (when the inactive window is displayed instead of minimizing),
When an email arrives in Gmail, the email app syncs within seconds and you'll be notified that you've received the email.
(2) However, if you minimize the email app to the taskbar, it will obviously not sync your email for more than a few minutes.
(3) Also, even if the mail app is not running, it is running in the background, and every few minutes or every few hours, synchronization will be performed and a notification that the mail has been received will be displayed.
In other words, if you don't keep the mail app window open all the time as an inactive or active window, Gmail won't sync immediately.
In case of (2) and (3), what should I do to synchronize frequently?
Minimum synchronization frequency of the mail app,
Frequency of synchronization at background startup,
So I think there is a registry setting somewhere, but I don't know where the registry is.
Even in case of (2) or (3), I want you to operate like (1).