Open a task in almost any other app and somewhere in the detail view you'll find a little dropdown that says Priority, with four options, and it will be entirely your job to pick one.
So you pick. High, probably, because you wouldn't have written it down if it didn't matter. Then you do that thirty more times over the next two weeks and now everything in your list is High, which is the same as nothing being High, and the field you were supposed to use for sorting has quietly become decoration.
The deeper trouble is that the label freezes. A task you marked Medium three weeks ago is still Medium today even though it's now due Thursday, even though the thing it was blocking is now blocked, even though it takes eleven minutes and you have twenty. Nothing about that dropdown knows what day it is.
Four questions instead of one
The ♥ score is a number from 0 to 100 that IHC works out for every task, and it's answering a different question than Priority does. Not how much does this matter in the abstract but what is the best thing for you to pick up right now.
It's built out of four things.
How critical it is. Consequences of not doing it, essentially. Some tasks are load-bearing and some are nice, and the app reads the language you used to figure out which is which — a renewal reads differently than a browse.
How hard it is. Effort and time, estimated from the task itself. This matters because "important" and "expensive" aren't the same axis, and a list that ignores cost will happily recommend a four-hour job at 4:40pm.
When it's due. Not as a binary overdue flag but as pressure that builds. Something due Friday is a different task on Tuesday than it is on Thursday night, and the score moves accordingly.
What else is going on. How much of your budget is left today, what you've already finished, what this task is blocking, what's blocking it.
Those get combined into one number, and the number is recomputed constantly rather than sitting where you put it in March.
Why it's deterministic
Every part of that math is fixed and repeatable. Same task, same day, same context, same score, every time. There's no randomness anywhere in the scoring path and there never has been.
That's a deliberate constraint and it costs us some cleverness, but a prioritizer you can't predict is a prioritizer you can't trust, and a scoring system that shuffles its own answers is just a slot machine with a productivity theme. When the top of your list changes, something about your actual situation changed. You should be able to look at it and go, right, because it's due tomorrow.
What it's for
The score isn't there so you can admire a well-ordered list. Sorted lists are easy and mostly useless.
It's there so that the first item is genuinely the right item, which means you can stop doing the thing everyone does — opening the app, reading all nineteen tasks, weighing them against each other, feeling slightly worse, and then closing the app without starting anything. That loop costs people more of their day than the tasks do.
You have a number of hours. IHC works out what actually fits, orders it by what will hurt most to skip, and puts the right one on top.
Then you do that one. Then the next one. Then, at some point earlier than you expected, there isn't a next one, and you're done — which was the entire point of writing a list in the first place.