What a pain! So if there are only three terminals in the block then I could get by by using one 6mm tail only but if there are three sets they have to be strapped out. Did you use 2.5 for the straps.
It was quite a while ago now, but I don't think 3X 6mm fit in the blocks, so I probably used 2.5mm for the straps, also for the earths straps (sleeved), these straps (links) were only about 40 or 50mm long or even less.
I know the instructions specifying 3X 2.5mm 'tails' adds up to 7.5mm, but you are using only 2.5mm per internal circuit and the supply cable fom the DB to the isolator and connection plate is only 6mm for the rest of the entire run.