While using a catalog can be a better way to organize photos, it usually is only a better way if you take advantage of the benefits of using a catalog. If you ignore the benefits of using a catalog, you are no better off than if you organized in your operating system with folders as the primary/only organizing structure, and you haven't streamlined anything, in fact you have anti-streamlined your workflow. In other words, in my opinion, you should use one catalog for ALL of your photos (streamlining your workflow), and then a rather flat folder structure (by capture date works) with keywords and other metadata used as your method of organizing/searching.
With regards to your specific problem, it sounds like you are saying that after you close Lightroom and re-open Lightroom, then Lightroom cannot find the original photos. Is that right? Have you moved the photos somehow after you import but before you re-open the photos? Are there question marks in the grey rectangle surrounding a photo? Can you show us screen capture?
By the way, could you use proper punctuation instead of a slash where you should be using a period? Thanks.