There are some issues that I think would make this difficult to do:
- Two employees at 50% salary and time are not equivalent to a single employee at 100% of salary. They're strictly worse if always run in series, all else being equal. Alice starts project X on Monday and Tuesday, and hands it off to Bob on Wednesday because it's urgent. There's some inefficiency there. Good management could help avoid it, but would be hard-pressed to prevent it in all cases. At best, it's one more thing to worry about.
- There are benefits outside of your salary that are more difficult to cut in half. Health plans, headcount taxes, etc.
