I ran sales teams for about 15 years before I started building my own systems, and the metric that fooled me longest was days-since-last-contact. It looks like the safe one. A lead you touched three days ago reads as alive. One you haven't touched in three weeks reads as dying. So you chase the three-week one.

The trouble is the counter measures your activity, not theirs. I ran a marketplace with over 300 merchants, and I used to go through accounts by hand because I did not trust an automatic flag to tell me what was actually dead. It worked at first, but it ate hours, and past a certain number you simply cannot keep checking all of them properly. The ones I had touched recently looked fine, so I skipped them. Some were already gone. I just could not see it under all the manual checking.

What I do now is track two clocks instead of one. Days since I reached out, and days since they last responded. When the second number runs much longer than the first, the deal is gone no matter how busy the activity log looks. A formula flags that gap on its own, the part I used to do by hand, but the call on what counts as a real reply stays manual. A calendar reply and a "leave me alone" reply look identical to a formula.