You're trying to get women to use logic when they arent wired that way. This will not work.It would make a lot more sense (for both parties) if the woman would come out and tell us when they want sex. I can explain.
A lot of guys are reluctant to propose sex too soon (as we don't want to potentially scare her away). We're forced to read her clues of whether she wants sex.
Here's the problem, however: Guys aren't mind readers. I have no doubt there have been many cases where a woman wants sex from a guy, but ends up not getting sex from him (because he isn't 100% sure whether he should propose sex).
The solution? The woman should propose sex. Hardly any men will say no. The woman ends up getting the romp she wants. The guy isn't forced to rely on reading clues. Win-win for both parties.
Your looking at it from the wrong direction.
You need to Take the lead. Women know you will want sex. That is a given. You the lead. They follow. You pursue sex when YOU want sex. Not if/when/maybe she might hope she let's me know...... NO.
You take the lead pursue sex, if she is Interested in you, you will have sex. If her Interest level is low you will not. Her reaction to you taking the lead will yell you EVERYTHING you need to know.
Waiting for her to tell you and have her take the lead will get you friend zoned as she will stop seeing you ad a date able option.