It all depends on what you want in your layout. I can't recommend enough the need to actually write out a list of what you want in your railroad and then see what you can actually accommodate. I would then think carefully about how you will operate your layout. For example, using your current layout design - as intimated in your other thread, if you intend to have the upper siding service the middle loop which runs counterclockwise do you have enough space to have two trains on the inner loop and access that siding? You can use the lower siding to allow another train to be on the main but will the train fit on the siding? Will the siding even be empty or will it have a cut of cars staged for some other purpose? Are you better served with double-crossovers to change loops so you'll have more space for trains changing loops?
It's perfectly ok if you want nothing more than loops to run multiple trains and or are limited in your budget to the track on hand, but it definitely seems that is not the case. Without thinking carefully about these types of operational questions you create more risk in not being happy with your layout once it's been built. That's what we want you to avoid.
-Greg