Q: Incremental or differential time machine?

http://pondini.org/TM/Works.html

Maybe this Pondini Time Machine article can address your question.

As far as I know, Apple has not released any technical documentation that describes how exactly Time Machine works with either attached or network drives ... so Google (or any search engine) is basically all we have (as fellow Apple product users) to go by. It you happen to come across any, please let us know.

Personally, I delete incremental backups all the time while beta testing new operating systems, and have never had an issue with a "broken chain" in Time Machine. Can't tell you why that is, only know what I see.

In eight years on the forum I've never seen a post from a user with an issue or complaint about a "broken chain". So, the hypothetical issue that you ask about likely does not exist.

Apple has not published any detailed documentation that would explain exactly how Time Machine does what it does. If you find another article that might explain the inner workings of Time Machine, please post back to share.

I'm assuming here that you will be deleting backups using the Time Machine interface. All bets are off if you happen to be thinking about using the Finder to go into your backups to select and manually delete items.  That is a no no.