I'm wondering why we don't make the vesting of the grant variable as well. Why four years? Why not allow an employee to negotiate for double the chunk for doub

I'm wondering why we don't make the vesting of the grant variable as well. Why four years? Why not allow an employee to negotiate for double the chunk for double the length of the grant? That's far more desirable than getting 4 years worth, arriving at year 4 realizing you've succeeded in building a company of true value only to discover that the amount you are re-upped is now at a strike price far greater (that you are responsible for achieving). i.e. you are punished for succeeding if you stay long enough to get re-upped.