Hi all
I know units are better in bigger sizes , 4 or 6 for infantry etc
But I have a theory that many small units might be handy.
15 point units are very cheap , if you take 6 units , a single company each or maybe even more to supplement your main larger units , you can use them as bait , deflecting units , flanking units , a skirmish screen etc.
Don't put any command or heroes in there , but just use them to get int the enemy's way etc while your main units get into position.

Has anyone tried this ?

I've personally found that units of 3 companies are usually pretty good. They're big enough to survive a few rounds if need be, but small enough to maneuver well, and if you don't include a command they can be nice and cheap. Of course if you're using something like goblins or orcs that's probably not the best idea since they'll probably get owned pretty fast.

I might try it out , half a dozen 15 point orc companies running around might be fun. If a large enemy unit wants to shoot at them then good it's only 15 points.
Could even give them bows to make them decent skirmishing units for 20 points a pop.

Absolutely
One thing a friend of mine did was to give them two handers, and then have Khamul accompany them. The two handers mean they can do some damage and Khamul's rule means you'll be able to kill just about any other formations through redirects.