There are instances when we are composing scenes for our stories we may consider that a specific scene(s) is/are unnecessary, and, hence, excise these. Maybe we are thinking that if we include extra scenes, this will slow down the story, or, add unnecessary material to our work. Sometimes this is necessary to do, but, many times it can be detrimental to the story to overly speed it up, or cut back on certain scenes. I have been personally finding this whilst writing a current project, but have also experienced this writing other stories.
What I originally envisioned as a short project, being around 1,000 words, is 3,000 words at the moment, and, may go higher the more I go into it. Certain scenes that did not seem as important in the initial stage gained momentum in the writing process, and, spawned more scenes, giving the story a depth which I did not foresee when I was writing the story breakdown. I am now pleased that this has happened, and, looking back, if I made the decision to not include these scenes, it would have made the story choppy, and uneven. I believe that this will assist the story to unfold at a more realistic pace, and, include the most essential scenes which are key to the story.
Everyone works in different ways with their writing. I find that I add scenes and (sometimes) new characters during the planning, first draft, or even whilst editing; it is just one of these individualistic things. What I advise is that we should not be afraid to just write scenes that may feel a little out of place in the beginning; we should just write these, and see what happens, you just never know what could emerge from all of your ‘meaningless’ pondering poured out onto the page!