I could see this being a great thing for non-elite levels. Maybe you don't want to spend time and money on choreography or costumes one season due to other commitments, or knowing you're going to move to a different region, change coaches, etc. Skaters could enter just for jumps, spins, steps/mitf or all 3. But you still get a chance to compete, parents & friends can come and watch, etc.
The jump areas could be marked out on the ice, spins could take place in the middle, out of the path of the jumpers.
I don't know how similar this is to what you're thinking of or what Aussie Willy is referring to...
In the US, it's common for nonqualifying competitions to offer Jump events, Spin events, and Compulsory Moves events (one or two jumps, one or two spins, and a step sequence and/or field move element). Less commonly I have seen some footwork-only events.
The lower level jump events and all spin events are held on half ice so there can be two events taking place at the same time on opposite ends with different judging panels.
(Juvenile and above get the full ice for their jump event. Compulsory moves events aren't really offered above juvenile level because those levels have short programs.)
The skaters each compete one at a time, with a time limit to accomplish the required elements. Therefore there would be no need to designate which part of the ice they should use for each type of element -- just that for half-ice events they need to stay on their half of the ice. Usually the host club has someone place traffic cones on the red line to designate the boundary more clearly.
Some skaters enter one or more of the above event types and nothing else because they don't have a free skating program (or entertainment program) to music prepared, as you mentioned.
Others enter one or more of the above in addition to program with music events. It's another opportunity to get the experience of competing, to earn additional medals, to include different skills that don't fit into the freestyle program, etc., etc.
They're fairly popular at lower levels, from very beginning learn-to-skate up to juvenile, sometimes intermediate, and also at adult competitions. I rarely see them at higher levels when I go to club competitions.
