You don't have to go down to 1 block , as long as you place enough diamonds in 1 block to stake within a day or 2 past seven, you will still be staking fast.
Try Splitting your stuff into 4 or 5 blocks , if they stake with 9 days, just keep your blocks with that amount in them, if they still don't stake within 9 days , then keep combining til they do if you want to stake fast.
If you don't want to stake faster ignore this use of coin control.
to merge together very small pile coin-control is nice (below 10 dmd pile size)
but once coin pile size is like 30 u dont have to bother
this pile easy merge mine together after 30 days and form 100+ size pile
u dont have to fear let coins age 30+ days because ur POS reward keeps increasing
pos reward deepend on coin-age
chance to mint a block deepends on coin weight
coin weight stop to grow after 30 days but coin-age still grow
so waiting longer for minting doesnt reduce ur POS rewards
destroy coin-age by use coin-control merge coin pile does
so there is two path i suggest
as someone who have lot small coin pile (below 10-30 dmd) u can one time merge them together with coin control
and later on let wallet keep doing its work automatic
if u have mostly coin pile size 10+ and some pf them 30 or more then do nothing
the 30 pile will easy mint after 30 days and by group stake mechanism add other small pile to this and merge them together
once again the target time to POS is 30 days not 7
7-30 days coin-age chance to mint a POS block with split stake is for big coin pile to be split in two parts and sometimes for lucky smaller pile