On the same device, app or web browser multi-factor authetication does not necessarily ask for approval every time. Immediately after the introduction of multi-factor authentication, approval requests may become more frequent as different devices and applications require approval to log in. Within time, the frequency of approval requests will decrease.

The frequency of approval can be compared to a debit card's local payment, where the pin code is requested at irregular intervals. Approval should automatically pop up on the phone screen when requested, and should also be displayed, for example on a work computer, as a notification that a approval login is required.
An example image of an approval from a device: