Unless the company messed with you severely this kind of moves is the worst. You make the rest of your co-workers unexpectedly carry your load. Essentially punishing your co-workers because you are leaving.
That and (depending on the state) they don’t have to grant you leftover vacation. I’ve has friends who planned this and then the employer accepted their resignation “effective immediately”. Not only did they not get to help usher along their replacement but they left thousands of dollars worth of vacation on the table
I agree but the companies also need to manage this risk by making sure people actually use their leave. If you have someone nearing the end of the year, appraisal time, with 6 weeks leave then you may have an issue