The F thing seems to expect a steady amount of maintenance to be involved in the friendship. At least, I see SFs especially having a tangible set of criteria that have to be met in order to prove that the relationship can be labeled as intimate or friendship or a marriage or whatever... (i.e., talk so many times a week, or certain types of life events must be related to the other person if they're in the inner circle, or whatnot).
I relate a great deal to DTS's comments. I actually still tend to think a bit even about people who I didn't overly connect with, just because I'd like to feel a rapport with everyone; but there is just this assumption that, if we talked deeply in the past and/or clicked together, and nothing changed or no one was notified of something changing, then things are still the same as before, and the connection still exists... regardless of the time or distance involved.