A conversation is a two-way exchange with a person. A call they answered, a reply to your email, a meeting. Attempted calls are worth logging — they just don't count toward the 15.
The notes box is on every lead. Type in it and it saves about a second after you stop. Write what actually happened: who you got, what they said, what the objection was, what you avoided doing and why. The Friday check-in reads every note — it can only tell you what you're doing wrong if you tell it what you did.