One of the most polarising subjects in the knife world are serrations. Some people hate them and some love them, personally im in the latter group as I believe they are one of the most under utilised blade types in the industry.
Let's start with how a serration works;
Each serration has a point and this point is the power part of the blade that contributes to ninty percent of the work. They puncture through the object you are cutting leaving the valleys to slice with the remainding surface area.
A plain edge blade also has serrations in it when sharpened correctly but on a microscopic level. It will require more force or a thinner geometry behind the edge to cut at the same rate as a serration on harder objects. Serrations have solid points can take a knock around and still be a point for a long time, this in turn means that you will end up touching up or sharpening a plain edge blade far more often (dependent on manufacturing quality obviously).
When it comes to what serration to choose I believe the width of around one centimetre in a standard dome shape serration is the best overall when it comes to kitchen duties, performance and ability to re-sharpen when required.
What about smaller serrations?
Well if speed isn't an issue when chopping up food for meal prep then yes they are usable however, you will get more achieved with a sharp plain edge in this case having the ability to chop and slice with less overall movement.
Serrations are great for bread and meat and are always a handy alternative if you need to cut something when all the rest of the knives in your kitchen couldn't cut butter and you forgot to ring your sharpener again :)