It depends, but you usually don’t need to empty the dustbin after each use. Many robot vacuums can self-empty at their docking station, so you don’t have to clean the actual robot.
Self-emptying robot vacuums can collect anywhere from 30 to 60 days’ worth of dust and allergens, which makes cleaning a breeze.
Other robot vacuums don’t offer self-emptying features but are more affordable. Depending on how much dust and pet hair is on your floors, you may be able to go a few uses before emptying the dust bin.
It’s worth reading the product description, as it will state whether it offers a self-cleaning option alongside how long the bin will last between sessions.
Source: Robotics - zdnet.com