I would argue, that the crawl budget is NOT, how many pages a spider will visit - the google bot only comes over and saves what he saw. The real performance intensive stuff is the evaluation of the data, that's where google is budgeting

You can see that by the index pages, that grow step by step, like there is some kind of limit to it, how many pages are processed.
The steps are because I take breaks, not because they weren't being indexed fast. I think I mentioned it before but everything will usually be on the serp within a day, and available to be clicked on and everything.
All these bumps are on days I'm publishing hundreds or thousands, all other time I'm not even touching the site cus I have other things going on. The requests will expand to fit the ton of new posts the shrink back down to levels of just freshness crawling.
That very first red arrow is the crawling for the first 4000 posts I published and I thought that was crazy, but even afterwords ive
come to find out I can even publish 10 k in a day and it would all be indexed and serving before nightfall (hence the more giant bumps)
Im not sure how to show this to you but I published arround 2 k posts yesterday and this is the last one I published before taking a break.
Already in serp with all the rest.
I dont have posts being published or made when im not awake as I am a little control freak with the Keywords and fear of the generation getting broken (which it has before and generated like 20 posts of nonsense) which sadly get indexed so fast that even though ive deleted them, they are
still on the serp cached lol.
Those flat areas where thousands are not being added to the index is purely because I wasnt publishing anything. Now the site has thousands, single posts dont even move the bars visually.
Some days ive published only a hundred (little bump) somedays ive had to delete a hundred (bot created nonsense, or something else went wrong so I needed to get rid of the posts )
Though keep in mind im not saying your arguement is wrong, im just saying I am not sure it applies to my site because these stairs are me chilling and not doing work for days then coming back and doing a massive job and leaving again.
If it was constand drip feeding the index from the crawled pages then it wouldnt look like stairs as every single day would have new posts being added. If I run my mouse on days you will see nothing at all is being added ( because nothing is left to be added if im not publishing)


TLDR:
The limits you are seeing is me being lazy and not publishing, not google avoiding indexing the pages.
Google has no pages left to index that is why it goes flat at random points.