I think this is something that originates from bitcoin and is not specific to Proof of Stake, but to be honest I am not sure about this.

@Biomech thank you for the explanation.
But for other POS coins there is only 1 wallet address of is something in the source we normally not aware of but is used in HyperStake?
If I follow the steps correct to make blocks with the right value 1000-3000 then I can not get extra addresses only when I send HYP to an other address and the block is not completely consumed. Using coin control I can prevent that by just split a block into 2 new blocks and one block has the amount I want to send to another address? Correct?

Well, I am heavily invested in several POS coins, and they are all like this. Perhaps you were just unaware of it, or others have implemented mechanisms that change this behind the scenes. (Sync does this, so I know it's possible). However, the ones I have the most experience with, TEK, HYP, FIRE and HBN, all have this same mechanism and all handle it similarly, with a custom change address available.

I normally let it split into multiple addresses and recombine as I see fit from time to time, but I can see where from the point of view of not making regular backups that could be a problem. On the other hand you can schedule a task to back up wallet.dat quite easily in all major OS's out there. I confess with pride that I'm a geek, so I fail to see the problem in this.

it's important for who have 1 or 2 address on wallet ?

I don't understand the relevance. Blockchain is transparent anyway. I'm willing to be convinced of the actual usefulness, though.
Useful feature (who at more transparent experience, particularly in the context of the coming Hypiggy): optionally deactivate change address (either deactivate it completely, or transparently use the main address as a custom change address - the latter only works if you have just one address in your wallet, though).

HYP/BTC market is live :-)
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My post it mean about use command "keypoolrefill 500 or 1000" it's important for who have 1 or 2 address on wallet ? not include normal backup.
I backup wallet.dat (File->Backup Wallet) everyday and Core backup (C:\Users\****\AppData\Roaming\HyperStake) every 2 days.
it's enough? , I never use S4C option.