At one point WTHI had over 250 variables. After some trimming down as we went we got it down to 150ish now. Keep in mind just a single girls date variable can have a dozen or more "stages" that are hardly straight forward and the game is so complex with the interwoven way the characters will interact with the MC based on his choices, both with them and other characters, that people who have tried to do walkthroughs (besides us) could at best manage to lay out a single path which explored the most content. Then most of them gave up.
As for our QC team, they are great at finding the typo's and variable snafu's on the main paths, but given the way so many variables can end up interacting in the game it would be near impossible for a small team of 10 or so guys and 3-4 devs to test everything. There are literally times we won't see an error crop up even post release for months. Then have a single report from a patreon that just happened to take a particular set of a dozen choices through the game that ended up with something unexpected.
I have played thousands of other AVN's here and even started with the old-school Japanese AVN's. I know I'm biased, but there are none I have played that match the impact of choice WTHI has on the narrative, both in the story arcs, and for the girls involved. But don't take my word for it. Give it a try.