[cflsystems]

The learning curve is way more than huge. It is not only OOP. You need to learn Doctrine too and Twig. And Vue. And MVC....

Not to mention the XC5 model going back and forth between templates and php scripts, the mix in code when one thing runs from js another from script and another in template...

The lists define some logical structure of data output and the order the data is shown.
If you have List A and you call List B from it List B will always show within List A and not show if List A is hidden. The weight determines the order templates show within the list. Weight of 100 will show the template before another one with weight 200.

So for example if you have stock cart with List A and some templates showing in it and you want to add another one somewhere in between you can set your template weight to a number between the ones you want to show it to. The cart rebuilt will modify the end list order.

Lists in XC5 show not only in templates but in PHP scripts too so good luck trying to find some consistency. The new webmaster mode is a big help of course - use it.