I'm kinda meh on the "should elections happen simultaneously or not" thing, although I don't think they suck away interest from one another. One can make the argument that following multiple elections simultaneously can be rather overwhelming for an average Legislator, but YMMV.

It does create a burden on the EC to run two elections side-by-side (remember the barrage of special elections we had earlier in the year?) and might cause inherent burnout issues for the position, so that should probably be kept in mind.