You don’t have to use illustrations at all. You don’t need a catchy illustration at the opening. You don’t need to illustrate after you state and locate and explicate. You don’t need an Illustration File.
If you want to save time on sermon preparation, cut out all the time thinking about, researching and honing your pretty illustrations.
Much of the work of illustrations can be done by good delivery, vibrant exegesis and concrete application.
And after you’ve gotten over the stagefright of public speaking, a trickle of illustrations will probably come to you on the spot, without careful planning and tweaking.
This is to some extent dependent on a mix of skill, personality and taste. So not everyone will be able to or want to take this advice on board, and that’s fine too.