Thoughts on cadence sensor?

What’s the general consensus on a cadence sensor? My tcr has a spot for one and I’m thinking about picking it up. I know it’s not as useful as a power meter, but I don’t know if I can justify a meter at this time. I’m a casual rider looking to increase speed and endurance. I’m currently a 18.5 mph solo rider and 20-21mph group rider.

Thanks