If one prisoner tastes all wines till he dies, there will be only one casualty. Numbers of tastes done would also be less. In worst case it will be 1000. However, in the suggested approach, it will be number of 1 bits from 1st bottle to 100th bottle.
You also need to spent time less than 5 weeks
if one person drinks one glass or one sip from all bottles, result will come after a month.
One casualty is minimum.