That's really personal preference. Some people advise to leave the B2 on most of the time to avoid the wear on parts that comes with turning power on. If you choose to leave the unit on, you might consider adjusting the display brightness and setting the screensaver mode to avoid premature aging of the display.
Screensaver
Settings > Maintenance > Screensaver
Settings for when B2 is in standby mode:
0 = Screensaver is Off
1..15 = Display Brightness when in standby
1=min, 15=max
16 = Display Off when in standby
Brightness
Settings > Brightness
Settings for when B2 is in normal use:
0..15 = display brightness,
0=min, 15=max