As far as I noticed the length between two points that doesn't get recognized as a pipe is 0.002mm.
It no doubt has been done for programming reasons there the route has to connect from point to point but by filtering out the ridiculous small disctances it means that the program knows not to draw a pipe entity nor that it has to keep track of those in the BOM.
In other words, when the distance between fittings is small enough then it won't count as a pipe. No need for you to make gaps between fittings connected to fittings.
If you want to make sure that there's no pipe between fittings, don't forget the 'remove pipe' command.
I didn't know about that command "remove pipe". I'll check it out.
Have a look at the route properties as well, if you have a value on the weld gap.