When you have this situation: - Many Apps - Each App has its own Data, Sources, Jobs, Objects, Styles, Variables, Dimensions, Master-Items etc.
Goal: You would like to create one App which includes some Objects of the other Apps. To avoid rebuilt and reload the same data you need an effiecient way. You have already what you need, you just needs to collect it and combine all.
How to achieve this? You can store some tables of each App in a qvd. Then in your one App you can import thess qvds.
Advantage 1) A lot of Data are very fast loaded in your one App 2) You need only one Job to keep updated your one App
Disadvantage 1) To store some tables (how is written above in "How to achieve this") needs some work. You have to do that with caution, as you can not export each table 1:1. You have some loops, temporary table, mapping tables etc.
2) All your variables, master-Iterms, color dimensions etc. are gone! You have to rebuild everything again! you have to, because you can not copy/paste nothing! No Sheets, no Objects, no Variables, nothing!
3) Once you have "rebuild" everything in your one App... you realise that the maintance of your apps will be a big pain. If you are going to change something in one your source-App, you have to do it also in your one App!
This is awful! Everybody is talking to bring data together, you will have great benefits etc. and then you realise that Qlik is not your good partner in that matter.
The reason why I build Master-Items and Variables is to be flexibel with a long-rang view. If I had knew that there is no benefit with it (in Qlik), I had never build it! Now I have exactly the opposite. My Master-Items and Variables are obstacles in my work 😞