I do that all the time. I, by instance, always group a condition and its else under a blank one.
I think that the readability beats any minor drawback.
Not advisable for people with the free version, amount of events run fast out of the max allowed.
Yes, I think I really understood ELSE statements when I started using sub-events, I think subs are my favorite feature of C2, not to sound like a total nerd! :p