Is it advantageous to store all linked list nodes’ pointers together?

It's worth noting that if you create an array or dictionary of pointers, you'll need to keep that updated when nodes are added or removed. Managing those updates can be tricky to do in O(1) time, especially if your list grows large. You'll have to make sure your auxiliary structure also supports O(1) operations for insertion, access, and deletion.

Regarding your question about achieving both O(1) access and insertion, unfortunately, I haven't come across a data structure that meets those needs. However, using a counted balanced tree might be a good approach. It allows you random access and insertions in O(log n) time, which can be useful. You would just lose the sorted aspect of the tree.

That idea is interesting, but it strays a bit from the definition of a linked list. When you use an array of pointers, you're essentially using a different data structure. This works well if you have a smaller number of larger objects, although insertion and deletion might hit O(n) in some scenarios — not always ideal!

It seems to me like what you're really outlining is an array instead of a linked list, which changes the fundamentals of how you manage the data. This could be beneficial, depending on your specific use case.