How often does a smartphone send a probe-request to search for Wi-Fi?

Question

Computer networks

Suppose the smartphone is in the user's pocket, it is not connected to any of the familiar Wi-Fi networks (there are none, for example).
How often will probe requests be sent by the smartphone?
2. Will they be randomized to hide the MAC address, always or are there exceptions?

Answer 1

1. From 10 sec to 1 min. Depending on the manufacturer and OS
2. Depending on the manufacturer and OS