The challenge for small batch brewing is consistency: is the next beer the same as the last. Well the short answer is “mostly”.
Every time I brew a batch of a particular type of beer I use the same recipe and method. But like baking a cake it always comes out slightly different. That doesn’t mean the processes have not been followed or that the “quality control” is poor, just that things are slightly different every time.
The ingredients might be called the same thing, but each harvest is different and changes with storage. The process might aim to use the same temperatures and durations, but the enzymes in the barley can be really firing today or the thermometer might be slightly off or the yeast is having a bad day. So there is a natural variation in each batch.
Now I think that is great. I expect the beer to be “good”, but sometimes it just comes out plain exceptional. And I simply cannot tell you why.
On top of that there is the “development” of the beer. By that I mean slight changes to the recipe either forced by circumstances or by design. So feedback on a beer might be that it’s not carbonated enough – easy enough to correct. Or that the beer is too bitter or not bitter enough (again correctable though less easy). Sometimes it is the availability of the ingredients, especially hops, and how they are treated (pellets are very different to use than flowers … I use both).
So small batch beers made by hand will have a natural variation which I don’t seek to eradicate. That’s the human element which I value in just about everything. Take out the human element and you get the blandness of mass production … cheap but at a price.