Interestingly enough, if you talk to anyone who actually knows what they're talking about a work schedule set by the employer is actually a minuscule bit of the IRS's three tests. Tenured college profs, for example, only actually have a set schedule on when they have to teach classes. Their office hours, when they're doing research, etc. are their own damn business. Even the much abused Associate Prof is an employee, and they don't even have to be in the state except for class time (which is negotiated with the school, not set from on-high) or office hours (which is set by the prof). Just about any high-level employee can similarly re-negotiate his work schedule and get a paid half-day off to help out at his kid's field trip.
It's also incredibly easy to find examples of contractors who have set schedules. You get hired as a contractor to fix an interior door in a building which is locked except during office hours, and the contract specifies you don't get paid unless you're done lickety–split, plus a nice juicy bonus if it's done tomorow, guess what you're doing from 9-5 tomorrow?
At-risk capital is much more important (Uber drivers own their vehicles, so they do have at--risk capital which indicates contractor), as is employer control (and since Uber drivers are damn near paranoid about pissing off the company, and act like Uber controls them, it does indicating employee), as is the nature of the business (if Uber's lawyers are right, and they aren't a transportation company this indicates contractor; if anyone sane is right and they sell cab rides it indicates employee).