I've kept a few of these and it seems if the plant is content having small leaves, then it won't really ever develop the huge ones. I always plant new bulbs/sprouts in a pot first to make sure the root system has a chance to grow first. Once it has a good root system, replant it with a root tab and watch its bollocks grow. :nilly:
If you trim the new leaves reaching for the top, the plant will be "trained" to remain short. If you let the leaves float to the surface, then all the new leaves will be floaters. You have to be careful since 1 plant can cover half a 55 gallon once it reaches the surface, so all your plants underneath will be shadowed. On the other hand its a nice shelter for your fish.
Here's one of mine. The largest leaf is around 6 to 7 inches. I just recently replanted this one and the newest leaves are always bigger than the oldest ones, and the old leaves tend to rot away from being overshadowed.