The Thinking Game
I even find myself wanting to go looking for the plant growing in the local area. In my story, parts of the plant are put into a juicer and then used to spike the drink of the unsuspecting victim. I've actually thought about trying to produce this oil for real in a juicer, but am thinking it may be just a little too dangerous. I'm sure that I'm already on some government watch-list for all my Internet research on the plant.
The point that I am trying to make here is that all this research, and planning, and thinking, has been for just a portion of the story idea.
Why so much attention paid to just this one item? Because I want the story to be realistic. I surely would not want some reader to go out and try this themselves but I want them to think it could be done - even if it cannot.
Whether one puts these thoughts down on paper or files them in their head while (or before) writing is a matter of personal preference.
So fellow writers - stop being so hard on yourselves. It's Okay to spend some time thinking about what happens, and to whom, in your stories. Yes, it is equally important to write consistently, but I believe that allowing your mind to work out the little things - to "game" facts, assumptions, and things you have to make up to fill in the blanks and keep things believable.