If you have a MIDI keyboard attached to your computer you can enter music very quickly.

• In the Edit->Preferences dialog under Audio/Midi tab select your controller
• Select Use Rhythm Entry for MIDI in
• Under the Input menu choose MIDI input
• Play some notes - they should appear in the score
• Press a number key to select a duration - a brown note of that duration appears
• Play in some more notes.
• Note that you can enter in more than one duration, then just play the notes over the top.