I understand some of the advantages of toe picks for freestyle and pairs skaters - they help you vault into jumps, by converting horizontal into vertical momentum. On landing, they help you convert vertical into horizontal momentum again.
And perhaps the sharp corners at the back of the tails can have a little of the same effect, especially in forward landings.
Both also make take-offs and landings "cleaner", and perhaps faster, in that there is less skid.
But at most ice dancers do quick small half-rotation jumps, and don't earn many if any points doing so.
Toe picks get in the way all the time. The tails corners aren't as bad, but don't seem to do much good.
Both slow you down, a lot, because you can't roll through as much of the blade during forward and backwards stroking (the tails drag if you roll back too far, and every figure skater knows the problems with toe picks if you roll forwards too far). Which I suppose is part of why speed and hockey skates use rounded fronts and backs.
So I've been unsure what use toe picks and sharp corner tails are for ice dance.
I was told by a coach that at one point in school figures days, forward 3-turns were supposed to use 2 points of contact, and would ideally create an oval (loop) tracing on the ice. E.g., on a LFO 3-turn, the toe pick would trace out the left side arc of the oval, while a point further back would trace out the right side. But now people don't look that hard at tracings, and in any event it is now more common to look for V-shaped tracings, corresponding to a single-point-of-contact, close to the sweet spot.
Am I wrong there? E.g., do the best ice dancers do a forward 3 by just barely touching the toe pick for an instant?
You could use the back corner for 3-turns, and other back turns, but that doesn't seem very common.
You can toe picks to help push strokes - but that is a no-no in figure skating. The best skaters never do it on purpose, AFAIK.
No one good seems to use them for twizzles, crossovers, progressives, swing rolls, edge changes, stops, or anything else that I've noticed.
Yes, there are choreographed moves that use them - pivots, and hopping or walking from toe to toe or heel to heel - but they don't seem common enough to justify the nuisance and speed drop the rest of the time.
So what are they there for?