It is more subtle than you think. It is not that you give no information about how to do things, you lay out all the steps that you took in your methods section. An example of keeping all tricks to yourself is that you do not tell others about the 100 small thing you found out, the hard way, that you should avoid doing. i.e. You explicitly say in the methods section these are the steps I took, but what others really need to know is why you ended up doing all the tiny tiny things it the particular way that you did. In many cases, you could write pages and pages about all these reasons. All these little tricks add up to much greater efficiency. Good experimentalists are the ones that have already made all the mistakes.

Edit: This is additional context for the commenters below.