Did you seriously take him at his word that he would text you at a particular time/date, and that you were obligated to not reach out to him until then?
Yes, 3 day rule is stupid. I imagine it was developed over time by people who just have to dramatize everything.
You want to communicate with him, do it.
Yeard ago I had a friend which I spoke with often, like daily. I think it was when we were in high school or college.
Anyway, I realized I hadn't spoken to her in 3 or 4 days, so I gave her a call. BTW, I'm female too. I said "hey, what's up, I haven't heard from you." Her response was the "you said to me at the end of our last phone conversation that 'I'll give to a call'"
I guess that meant if her pants caught on fire, she wouldn't have called me to tell me about it after she put them out.
I couldn't for the life of me tell you if the last time I texted or spoke to someone if one of us said anything like "I'll call you" or "you call me"
It's just an expression.