You can tell your wallet to manage blocks automatically using this RPC command:
setstakesplitthreshold <1 - 999,999>
For example, if you set your stake split threshold at 5000, the block will split when two new blocks are bigger than 5000, otherwise it will just add the stake amount to the previous block size. See this entry for more details.
After setting up the stake split threshold you only need to do an initial setup by SplitBlock feature (if you haven't already sized your blocks how you wanted to) which can split all you blocks at once, just select the size from this range: 4500-20000 HYP. See the video below.