You just spell your password in your mind and when the character is needed you press the key, when it's not needed you don't. The login site looks like this:

    [x] [ ] [x] [ ] [ ] [ ] [ ] [x] [ ] [ ] [ ] [x] [ ]

And when you press a key it jumps to the next empty field.

If you actually use random passwords, this isn't possible. You have to pull up your password in plaintext so you can view it in its entirety and manually count to the correct character,

This partial password stuff is just utter garbage. It's lower security than a typical password, way lower security than multi-factor auth, blocks use of password managers, and is generally inconvenient for no good reason.

I don’t spell passwords in my mind; I have muscle memory for the password.

Well, yes, it's slower. But not by much. A few seconds.

Some of my passwords I have memorized only as muscle memory. Without going into too much detail, if I didn’t have a qwerty keyboard, I wouldn’t be able to enter it without a couple minutes of thinking “okay, this key is there on a qwerty keyboard...”

I create my passwords from long, easy-to-remember sentences that I sample to be like 15-25 characters long with capitalization and special characters added in a pattern.

Makes it easy to remember the password without muscle memory.

This means you're re-using passwords. There is zero chance that you remember hundreds of unique passwords for all the different sites you need access to. Good money says that your pattern is extremely predictable and anyone who sees one or two of your passwords has enough context to know the pattern for all other passwords.

I have exactly the same issue with my passwords. I can remember what the letters, numbers, and symbols are, but I can only remember which letters are uppercase by typing it out on a keyboard.