I have no direct experience with scaling DynamoDB in production, so take this with a grain of salt. But it seems to me that the on-demand scaling mode in DynamoDB has gotten _really_ good the last couple of years.

For example, you used to have to manually set RCU/WCU to a high number when you expected a spike in traffic, since the ramp-up for on-demand scaling was pretty slow (could take up to 30 minutes). But these days, on-demand can handle spikes from 10s of requests a minute to 100s/1000s per second gracefully.

The downside of on-demand is the pricing - it's more expensive if you have continuous load. But it can easily become _much_ cheaper if you have naturally spiky load patterns.

Example: https://aws.amazon.com/blogs/database/running-spiky-workload...