What are the benefits of consistent iPadOS updates?

Apple recommends to update your iOS as soon as there are firmware updates or upgrades, to improve security and the functionality of your devices.

Have a look at this Apple page:

Apple security releases - Apple Support

Updates will also fix software issues for apps, for example.

AbooAsma wrote:

What are the benefits of consistent software upgrade?

Apple makes more money.

I will like to find out why an apple user needs to continue software upgrade. It is compulsory or optional?

It's entirely optional. But you have to have nerves of steel. Apple will bug you, literally every day. They put a big red alert in the Dock telling you that something's wrong. You will hear constant (DANGER!!!!!! UPDATE YOUR COMPUTER NOW!!!!) alerts posted on social media and mass media. It's all fake. Every bit of it.

Apple really doesn't participate in the fakery beyond the red badge and some notifications every now and then. But they certainly reap the rewards of more frequent updates and then more frequent hardware purchases.

If you wait until after type hype dies down, then you can do the upgrade if there is something about a new version that you really, really want and your device is less than 3 years old. Currently, that would mean Ventura. Sonoma is still being regularly broken and updated. With Ventura, you know what you're going to get and you know it isn't going to change very much, if at all. I run Ventura on a newer machine because that is what it came with. It can't be downgraded. My older computer is still on Monterey and I'm more or less happy with that. The only problems I have are external. The computer itself works fine.