You have the strongest negotiation power with other companies at year 2 assuming the stock has done well. Companies need to match/exceed your projected comp 2 years out, and for some reason are more willing to do so when someone else is paying you at a certain level.
At Amazon you may face a cliff in year 5 if you haven't been performing at the 80%+ mark for your level and haven't been promoted in the last 4 years. At the higher levels where advancement is more difficult this increases the incentive to lock in a 4 year compensation package of your 3 & 4 year comp.
I didn’t like working there for normal, pedestrian reasons: dead-end project, mediocre code, difficult-to-use tools. The next job I got was substantially better paid because I got an implicit promotion.
