you shouldn't worry about that, I explain:
When you press a key in psycle, it acts like it was an instrument. It plays while you maintain the key pressed.
This is also done when entering the notes in the pattern, for when a user tries to record it live (i.e. while playing).
In the end, when you play the pattern/song the wave will not stop if you don't put a "off" note before it reaches its end.
<[JAZ]> Pa pi pa pa pa pi pa.... ;ĚD