as fast as possible implies spending the resources that way.

Going close to as fast as possible while saving a stream for the other approaches makes sense as an approach, but let's not ignore that there's a compromise/tradeoff here. Might not matter in orgs with near infinite resources

Also in an exponential competition environment, the difference between 100% commitment and 98% commitment is very possibly not even the difference between a win and second place, but outright lapping by the winner and humiliation at the scale of the gap for second place.

For an example of what this looks like at a more pronounced scale just look at the discourse around European models and how far behind Minstral are perceived to be.