It's depend on the consensus and how does it design. The interval value could be defined based on the calculated result and the capacity of network.
E.g: You defined the interval between block is ~ 2 secs, you might need to calculate following these thing:
Time for major nodes to reach an agreement to choose the next minter
A window of time for another ...
As this is an Ethereun forum:
Ethereum 2.0 proof of stake has inflation rewards for the validators that stake. You can find more information about rewards ad the proof of stake structure in this blog post of mine.