Question about lettuces
 

Hi Everyone,
I was recently surfing about online and I found an indoor aeroponic unit , called "aerogarden" and it started me thinking about trying one out.
But I have a question to anyone who grows lettuce. I suppose the whole point of such a system is that you can have plants continually growing, while you harvest small ammounts from each plant. Has anyone ever grown lettuce and just taken some leaves off of them at a time? I would have thought that the lettuce( the leaf stubs ) would mold, if not is it possible?. I was thinking that I would like to grow about 6 lettuce (Romaine) and just take a few leaves off each one.
Sorry for the rambling and that this is probably a strange question.

Regards