I've had end-to-end mountings, where both plates are flush with the ends.
When I have had 1/4" shorter blades, they are mounted flush with the front. The gap is at the heel.
Technique varies based on the skate manufacturer/model. Klingbeil prefers end-to-end mounting, whereas Riedell suggests the 1/4" shorter lengths. Jackson's stock skate sets are all over the board because the blade lengths don't match all the boot lengths. Sometimes, you will see a stock set mounted with a small gap at the front as well as at the heel because that's the best way to make it fit. (That's also why Jackson's laces are incredibly long - they try to carry as little inventory as possible, so they use the long laces in multiple sized-boots.)
Don K. Explained that his skates have a smaller sole than the comparable sized skates from other mfgs, so he prefers end-to-end. He said that, if you looked at the edge of the sole, it was smaller than the leather upper. He said other mfgs' soles come out past the upper. I couldn't find any photos that illustrate that, though.
What really matters is having the toepick and rocker placed properly under the forefoot so toe jumps, spins and turns aren't a challenge. I've always felt that the problem with my stock Jackson Competitors was two-fold: a little long on the right foot, which put the toe rake and rocker too far forward for me to control.