Understanding manual search
Manual search is the most straightforward hyperparameter-tuning method that belongs to the exhaustive search group. In fact, it's not even an algorithm! There's no clear rule on how to perform this method. As its name would suggest, a manual search is performed based on your instinct. You simply have to tweak the hyperparameters until you are satisfied enough with the result.
This method is the one exception mentioned before in the introduction of this chapter. Except for this method, other methods in the exhaustive search group are categorized as uninformed search methods. You may already know the reason why this method is the exception. It's because the developer themselves learn what is the impact of changing a particular or a set of hyperparameters in each iteration. In other words, they learn from previous iterations to have a (hopefully) better "hyperparameter space" in the next iterations.