AKA Bent Branch Spoons
I love carving with straight wood. It's great to have a large round of clean, straight grained wood. It splits cleanly, popping out identical billets. You know they will all behave in the same way. Perfect for carving out multiple spoons of the same design. Handily, large rounds of wood are also the easiest for me to get a hold of.
The downside to carving lovely curvy spoons out of straight grained wood is that you start introducing weaknesses. We're all familiar with how wood grows in layers within the tree. Once the tree has been felled and you start carving, these growth rings are now the grain of the wood. Along the length of a spoon, the more contact one layer has with the next, the stronger that connection is. When working with a straight grain billet you need to layout the spoon so you get curves that don't cut across growth rings too sharply. It's easy enough to do, but you can't have extreme curves without creating a potentially weak spoon.
Fortunately nature has already sorted this problem out for us. Trees have been kind enough to grow limbs in the shape of spoons, curves already included. You can find these pre-grown spoons where a new branch grows out of the trunk or from a larger limb, or where a limb splits into two branches. Occasionally you can also find the right shape somewhere in the middle of a branch, but these occurrences are rarer.
Working with crooks gives me a sense of working with nature. It does however mean that certain decisions have already been made for me. To make the best use of the advantages in strength and thinness that a crook offers you are limited to the shape it has grown into. The strongest spoon forms will have the fibres running unbroken along the bottom of the bowl, where it needs the most strength. You should be able to see the growth rings exiting the front of the bowl. This ensures there isn't any short grain at the tip of the bowl, an area often subject to stresses from scraping.
Sticking to the way the branch has grown often results in a spoon that has less of a bend in it than the branch hints at. A 'mistake' people often make when working with crooks is to try and get the crookiest crook that has ever crooked from their crook. This isn't really much of an issue, you're just introducing weaknesses that you get in tangentially split wood. If you're aware of this you can plan accordingly and all will be good in the world.
Personally I enjoy working within the limitations the tree has set for me. It presents a fun challenge and encourages me to finish a spoon that most closely represents what nature started.