I use to work on mostly the top-down approach. Actually I prefer that approach but some times it gets messy. You know everything has its own pros and cons. when it comes to edit or update some feature or sketches made in assembly features and we want to change them in part environment. There I feel the area I want to have some solution or suggestions.
I have a strong desire that if I create a feature in assembly (may a cutout or hole) and when I select propagate to parts. Then instead of propagating a derived feature and sketch if that feature created in assembly mode gets propagate to parts taking all the sketch dimension with them and are still linked with the parent sketch in the assembly. Then I think I would get an ease to update the sketches in the child part without going back to the parent assembly. If this is something which can be achieved then the parts are independent for that feature and can be worked out for any change required without compromising the positions and avoiding the back and forth action.
If anybody have suggestion and solutions then please discuss.