Are elements of the Hash Table’s backing array Linked Lists from the initial point when using Separate Chaining?

As usual, did quite a research in different books and academic articles, but can’t really get a clear picture.

For the Hashing Collision resolution in Hash Tables, we have one very popular strategy for resolving it, and it’s called Separate Chaining.

I’m aware, that in the Separate Chaining strategy, elements, which end up being collided due to hashed into same particular index, are (or will be becoming) Linked Lists.

One instructor even said so, that:

Elements of the backing array in separate chaining, are linked lists.

My question is following: is the type of backing array Linked List from the moment of creation of Hash Table (during separate chaining strategy implementation), or it gets converted to that array after first collision? because, having Linked Lists as each element of the backing array means, that those Linked Lists, should be a list of the elements, which in turn, are Entries/Buckets of a pair of key-value. This all really consumes a lot of memory and resource, I reckon.

Thank you.