If the distribution length is 1/3 of one object width it looks like this, so another option would be picking the distance instead of putting in numerical value.
And watching how it changes, before the final click.
Then your length should be a minimum of 30 for 3 such cubes to be able to fit with 0 space between them. As you go larger than 30 then there will be spacing added between them.
< As you go larger than 30 then there will be spacing added between them.
OK ! Was not evident at first view! :)
Confusion (for me) between "on a length" and "absolute distance" between object...
that is an another one existing...
Is it a big deal to have in MoI a Scale option as in ScalePositions in Rhino?
Situation when you have several objects and you want to scale a space between them not the objects?
In Rhino it is even a polar option for objects arrayed circular.