Double click insertions
P3 - Low
S5 - Suggestion
While in edit mode, when you double click on an item in the palette, the item is selected when it appears, forcing users to press escape or place another note to double click another item. Escape will make them exit edit mode.
The idea is that by leaving it selected, you can more easily adjust its position, although these shortcuts have changed since 2.x so I'm not sure this is as easy as it used to be. Definitely worth revisiting at some point.
Anyhow, if you wish to add a different marking to the next note, just press Alt+Right to navigate there (left/right alone also work for navigation). If you want to add the same marking, better to just add it to both at once - select the notes you want to apply the marking to, double-click the marking in the score.