Considerations

It depends.

Mainstream/contemporary short story writing = Enough thought to have a vague idea of what is the plot then I write. I can do this because these are short stories about a character and the character is already alive and demanding the story! I 'know' the character well.

Historical work. Research research research until I feel comfortable in the place my character lives. Then write. This always means more specific research after the first draft and more writing.

For me to sit and plot and plan and think and worry means I've killed the story or produce a bland overwritten one.

It may be bad form, but I usually fly in blind on the first draft - that part of the process is all about getting the basic story down before the idea runs away from me. I'll use the handy highlight option in Word or write in a different color ink to mark things that I want to go back and verify or flesh out, and then do some research before the second draft.

In writing novels, I'm somewhere in the lazy middle. I research as I go. That way I don't have to learn anything I don't need.