Actually, class C makes things worse from a duty cycle perspective, since it has fixed air settings. Traditionally much slower air settings, though TTN EU cranks it up a bit.
What class C changes is that the nodes do not have to poll for downlink by sending an uplink, because a downlink can instead be sent at any time. Class C reduces how busy the network is in the uplink direction, since uplinks only need to be sent when there’s actually something to report.
However, class C only works with nodes which can run their receiver continuously, which basically means mains powered nodes. If you have mains power, there are a fair number of other schemes beyond LoRaWAN which could be usable and may make more sense.