Consider the case where the patron has the block already purchased. Perhaps long ago. Trying to find a sculptor willing to undertake the job of making something of it. Clearly the patron would like the largest sculpture possible, using as much of the expensive marble as possible. For marble, read facts. For block, read all the available information and relevant factors.
The marble block can be awkwardly shaped (and facts often are). The larger the sculpture the more or a constraint is the shape of the block. A small paper weight can be freely shaped from a block the size of a car. Any design and shape would be possible of the size if the finished item is much smaller than the starting block. The sculptor is without design constraint if he can chip away as much marble as he likes. (And virtually any position can be defended with impeccable logic if all inconvenient factors can be ignored. )
But if the assignment is for a wild animal perhaps a elephant is a better design choice than a giraffe if the block has the shape of an apple and as much of it as possible should be used. And so the design becomes more constrained.
The David was a masterpiece of making the most of very awkward block of marble – thin and long. Many artists declined to commission when they saw the block the City of Florence had bought for the purpose. Having seen a sketch of it in the Accademia that is easy to understand.
Some time ago I had occasion to read the print version of right-wing online news, debate and discussion forum. The editors had made a selection of the best articles that had appeared on the site. Having never looked at the online version I decided to give them the benefit of the doubt and buy a copy of their “best in show” pieces. It wasn’t bad. The articles I read were well put together and argued. But very narrow. The authors didn’t include much of the “marble”; They had taken David-size blocks of marble and carved beautiful paperweights.