Not only is it easier than writing an event sheet for each layout, but can make organizing better too.
For example, spread the game engine over a few different event sheets, all interaction with the player in one, all collisions in another, etc. Makes working one things easier.
Then make an event sheet for each layout level, with events specific to that level, and include the main game engine in that.
Other tips: Put all your global variables in one event sheet, since they are global, it won't have to be included in any other sheet.
You could also put all your functions in one sheet, (or two if you're function happy.)