If it comes to old friends, it's easy for me. Either you feel that both of you are still "on one wave" , or not. Both variants happened with me. At high school I had 2 friends. We were thick as thieves😂. After I moved to other city, student's life, then family life, work...
We met several times sporadically, but all of us were busy. Or maybe I was busy, frankly speaking.
When we met couple years ago it passed more than 20 years, I felt that with one of them we are still on one wave, but another is not:(
We go skiing together, and sometimes we call each other. Not often, and it's not necessary. We both know we can call or text at any time. Old friends are just like relatives.😂
But for new friends time is necessary, you are right, because you have no such a strong foundation under your friendship.