Physical fit and watt-density calculations do not establish system approval.
Do not treat TempZone cable in DITRA-HEAT membrane as a Schluter-approved combination. Schluter says it recommends and warranties only its own heating cables in DITRA-HEAT applications, because cable diameter and power output are matched to that membrane.
The old article’s approximate 2.5/3.5-inch spacing and watt-density estimates were not an installation approval. Follow the instructions for a documented complete assembly. For TempZone cable with Prodeso, use the WarmlyYours/Prodeso instructions and the project layout; do not transfer another manufacturer’s spacing rules to it.
Any proposed mixed-manufacturer assembly needs written compatibility and warranty terms for that exact combination before installation. A cable snapping into the studs is not enough.
Sources: Schluter’s other-manufacturer cable FAQ, TempZone cable manual, and Prodeso installation manual.