On various forums and blogs there's sometimes discussion about the size original comic art is drawn. Many years ago pages were usually drawn at least 'twice up' (twice as wide and high as the printed page) but over time editors asked for a reduction in size, usually to one-and-a-half larger than printed size (or 'half up' as it's called, being diagonally half larger than print size).
These days, with art being supplied via e-mail, there's no hard and fast rule about it. Back in the days when I was contributing to comics such as Oink! and Transformers I'd draw my pages half up, but in recent years I often draw them about twice up.
Basically, the larger you draw the originals, the less restrictive it feels, and the better the art looks when reduced. Although this depends on the artist of course. The late Jack Edward Oliver drew his pages the same size as published and still managed to put a lot of detail and incidentals in them.
The mini-strips I do for The Beano are drawn twice-up, as you can see from the size comparison in the photo above. I just find it a comfortable way of working. As you can see, the original art is drawn in blue pencil, then inked. I then scan it into Photoshop as a line drawing (which doesn't pick up the blue pencils), tidy it up, convert it to CMYK and colour it on screen. Then it's simply a matter of e-mailing it to the editor, along with the script for them to letter it. The physical artwork doesn't even leave the room, - a far cry from the old days of a parcel of artwork being posted on a long journey to London or Dundee!