You receive one free recruitment attempt at fixed time breaks for both the Legendary Recruitment and the Epic Recruitment banners.

Regarding the Advanced Recruitment banner, you receive a certain number of free recruitment attempts each day. 

The number of free attempts depends on the level of your "Hall of Heroes" building. The higher the building level, the more free Advanced Recruitment attempts you get each day.

Additionally, upgrading the building also reduces the cooldown time for free recruitment in the Epic Recruitment banner.