I can't say with certainty the reasons why these decisions were made, because these decisions were made many years ago and I wasn't involved in the development of this feature in any way.
From my point of view, some of the design choices seem a bit strange. My best guess is that the developer(s) were concerned about computationally loading the network nodes.
Why is there a 30 days period? can it be short or longer or daily?
Yes, it could be made shorter or longer. But we haven't done any performance analysis of changing this aspect of the algorithm (although my gut feeling is that there would be little negative impact from reducing it some). Truthfully speaking, we didn't want to spend a lot of time on this feature, we're mainly focused on developments that we believe can have a higher long term impact and I didn't think changing the interest rate period would make much difference.
Thanks for explanation.
Completely agreed. Keep the pace up ;)
I think another reason for the delayed payment is small balances. With a low balance, too-frequent interest payments could be <0.001 and you'd get nothing. There are other ways to solve this though.
Sounds plausible, although it's difficult for me to imagine anyone who should be deeply concerned about losing such amounts.
Possible.
But for someone holding a stable coin, 30 Days is a very large period to incentivize and then a 3 days unlocking period as well. I guess may be first interest payment should be after 30 days, but should be reduced to 7 days or more often after that. Else, holding fund for 27-29 days and then if someone needs to extract/move funds, he would be missing on some decent amount, which isn't great for big holders.
You don't actually have to hold for 30 days. You can only get one interest payment every 30 days but if you hold for one day then sell, you still get the interest but you might have to wait for it (and perform some transaction that affects the balance, even if only by 0.001)