does a 30 day block automatically stake?
so if i keep my wallet open all night lonng i increase my chances to stake?
what if i leae it closed for 45 days and open to sync?
it doesn't automatically stake after 30 days. At 30 days, the coin age (#coins * #days) is at it's max.
So if you open at 30 days, 45, 90 days or more. there's no additional benefits to wait longer. you have the same coin age.
Like Tranz said, PoS is just like PoW in that sense of competing to solve a block AND luck. The "weight" factor is used to discriminate younger blocks from older ones... but size does matter also (in the weight formula), so a small block will eventually stake, but it could take longer since their max weight is limited by their size.
You also have to understand how PoS works.
There is this "splitting" of the block that goes on when it stakes... so, even if a block of 100 HBN will likely stake before a block of 10 HBN, when that block of 100 HBN does stakes, it becomes 2 blocks of ~ 51HBN each.
So, over time (over 3-4 successful stake - 30-40 days) the original 100 HBN block will be just about the same size then that 10 HBN block.... but that 10 HBN block will have more weight because it's been sitting there for 30-40 days, so it will be closer to stake than those newly minted smaller blocks.
I believe the splitting was though of to
a) level out "big" stake holder with "small" ones
b) Secure the network since each successful PoS stakes creates a new block on the chain, the more blocks available for stake, the more secure the network will be against 51% PoW attacks since PoW and PoS are competing one another.
Another thing to understand about PoS "interest" is that it's 100% per year but each 10 days, you get a "chance" to be rewarded a part of that 100%.
Example: 365 days / 10 days (minimum wait period) = 36.5
So you have ~36.5 staking period in 1 year.
100% / 36.5 = 2.74%
So every 10 days, you get ~2.74% (this varies as it's also based on network parameters... I don't know all of them) return on your coins.
But what happens when it takes longer to successfully stake... well basically, that 2.74% will be bigger. Just for an example, if it take 100 days instead of 10 days, then you could expect ~27.4% return on that same block.
So you are still rewarded for waiting longer. You will lose the "compound" effect of staking more quickly but you still get a nice reward that compensate for the longer time it took to get your stake.
hope this clarifies things for everyone.
PoS is a complexe concept but a pretty cool one IMHO