I opened the largest of the SketchUp files included in the LayOut file… I corrected the incorrect tag usage (there was only one tag) and purged unused stuff from the model.
This reduced the file size by 81%. I expect if I do the same to the other .skp files I’ll get similar reductions which would further reduce the the size of the LayOut file.
I note that this one is basically the empty shell of the house and it is all loose geometry and there are some reversed faces. There should be no exposed blue back faces in your 3D model.
Here’s another example. Purging unused stuff from this file resulted in a file size reduction of over 76%.
It appears that you are creating separate SketchUp files, many of them drawn in 2D for the same project. It would make more sense to use a single SketchUp model file for the entire house project and create the scenes you need to show the various details. Much easier to manage that way and less chance of inducing errors when changes need to be made. As it is, if a wall needs to move in the project you have a whole bunch of files to go through to ensure that the change is shown correctly. If you had only one SketchUp model file to deal with, you could move the wall and it would automatically be reflected in any scene where that wall is shown.
You should check out the books offered at MasterSketchUp.com. I think they would be of huge value to you.