In Europe (EU868), the ETSI EN 300 220 regulation typically limits the duty cycle to 1 % per hour on the main sub-band, which caps the number of frames an end device can transmit (from a few dozen to more than two hundred per hour depending on the spreading factor).

On the EU868 main sub-band (868.0-868.6 MHz) the duty cycle is capped at 1 %, which means roughly 36 cumulative seconds of transmission per hour per device. Other sub-bands range from 0.1 % to 10 % depending on the channel. The practical consequence is heavily dependent on the spreading factor: at SF7 (fastest) a device can fit approximately 200 messages per hour, whereas at SF12 (slowest) only about 10 messages per hour are possible before exhausting the budget. On top of the regulatory duty cycle, many networks apply a Fair Use Policy that is even stricter than the ETSI limit.

Calculate your time-on-air budget at the worst-case spreading factor before deployment — ADR will eventually lower SF in good conditions, but the device must respect the duty cycle from its very first transmissions at SF12.