I'll agree with the majority (albeit not what you were asking about). Since a 5g batch is so darn small, and kits are just begging to be 5g batches, why not just do it?
If you're out of the game and are teaching a newbie, buying a brewer's best type kit is the perfect start to get back into it. Not to mention that 2 cases goes really fast, even if you only drink with your friend.
My first batch put out 2 cases, and after 3 weeks in the bottle I have about 8 beers left. I couldn't keep my hands off of them while they were bottle conditioning, so there's 3-4 bottles gone. I took 3-4 to a friend's house with me to share my new hobby. I gave another friend a 6-pack because he gave me a 6er of his first brew, and then we drank maybe 10 between my roommate and myself. Now I'm nearly out of beer and have to wait another month till my next batches are done.
No good reason to stay THAT small. Heck, after 3 batches of 5gal, I'm already wanting to go up to 10 gal just so I have enough to drink after handing out samples!