I have a mapping habit that I usually control the time line with the arrow keys to see the situation of previous seconds or to have a little view of new mapped pattern.
More specifically,when I add hitsound with playing the music,after I selected a note and add some hitsound on it(after that if I don't click the empty area,the note is still selected),I want to check how the hitsound works so I press "←".Then the note moved left and the time line can't be controlled directly.This forces me to change back the note to the place where it used to be.This doesn't make mapping easy but increased unnecessary troubles.
Another fact,sometimes I like to map the rhythm first than arrangement.when I come back to design the arrangement,after I have put one note to the place,I want to see how it shows with its previous notes(like if the shape is good,or the flow is good or not etc.).I need to press "←",still,it moves left but not to the time point I want.
In a word,this function doesn't make any benefit for me but brings me much trouble.To be honest,when I map with the function it makes me so annoyed that I nearly want to break my keyboard...
Maybe we can make a switch of this function (add a option in edit/compose etc.) or use number 2468 instead of arrow keys.but for now,I can't compliment it.