Let's say I have 8 clips playing. All SEND knobs have value "0%". I want to save this state in order to go back to this state after I changed a lot of values - e.g. I turned the SEND knobs on some tracks to "100%", changed some parameters of some VST plugins on the master, stopped 2 clips, etc.
Imagine you play something (e.g. the break of a track). You move faders, turn knobs. Then you almost at the end of the break and then you re-call the snapshot to bring the beat back.
If anyone knows the Yamaha SU700 ... this machine has 8 snapshot buttons where you can save the current scene by holding down one of the 8 snapshot buttons for 2 seconds. To recall the saved snapshot just hit the button where you saved the snapshot. This is an excellent live feature!