Measurement
Reading session-depth as a loyalty proxy
Journal · Switch Routehub · reading time about eight minutes
Session-depth is seductive. It is already in the analytics property. It rises when people click. Leadership likes a number that looks like attention. Used as a loyalty proxy without an exit taxonomy, it will classify confused billing users as devotees and classify efficient repeat buyers as cold.
Two depths that look identical
In a Thai subscription extract used in Loyalty Decay Diagnostics, high depth clustered in two places: people hunting for the cancel path, and people comparing plan tiers after a price change email. Both groups produced long sessions. Only the second group still prepaid ninety days later. NPS, famously, did not move. Finance noticed thinning prepaid volume first.
A third group — one-click restockers — had shallow sessions and high actual loyalty. RF alone would have treated them kindly. Depth alone would have buried them.
Exit taxonomy first
Before depth can be a third axis, you need named exits: purchase, save-for-later, support, billing, cancel-intent, bounce. If your event names cannot tell billing from browse, depth is noise. That is a hygiene problem, not a modelling flourish. Module 01 of the flagship room exists because teams skip this and then argue about weights.
Once exits exist, depth-after-browse can be a weak positive. Depth-after-billing is a warning. Depth-after-cancel-intent is not loyalty; it is friction. Mixing them into one “engagement” KPI is how proxies rot.
When we refuse depth entirely
App webviews that double-count, infinite scroll home feeds, and chat-style commerce inflate depth without a decision. In those products we have used category retreat or ticket tone instead. The Atlas allows only one third axis at a time. If depth cannot beat the alternative on a held-out quiet month (not a festival month), it stays off the score.
Loyalty Decay Diagnostics will not teach you to “increase engagement.” It will teach you to stop calling billing confusion a love language.