Interesting suggestion. I’ve had to correct a lot of tasks after interruptions and such and there have definitely been cases that fall into this category you describe. A “snap to adjacent projects” might be a good alternative to a simple default time increment for new tasks. Perhaps they can coexist together (allow snap to nearby entry when available, else default to time X). Say your default time entry is 1 hour. If there is a task before but not after where you drop a new entry it could snap to the location immediately following the last entry and create a 1 hour task. Same for a task after the timeline spot you drop the task on. And as you suggest a task dropped between two others might snap there. It would probably be good idea if “tearing it away” when it tries to snap returns it to “just put me where you want me” mode. I believe I’ve seen behavior like this in other applications but can’t recall a specific one.
This made me think of a similar concept. Most frequently the issue for me is that I get interrupted and I forget to switch at the correct time. I have adjacent time entries, they just transition at the wrong time. What I really want to do is drag the boundary between the two time entries and have it resize both simultaneously.
Of course some people actually want to have overlapping time entries, and you have to account for the fact that sometimes people want to create “gaps” between projects. So I’m not sure exactly how to accommodate the new feature while still being able to purposely create gaps and handle other use models such as overlapping tasks. But I can honestly say that at least 90% of the time when I’m manually having to edit my timeline what I really want to do is move the boundary between two adjacent time entries.