Building a wheel, spoke calc and DT Swiss calc said right side needed spokes to be 259.
AsI had a load of pre used 258 mm spokes I tried to use them (as they'd be stretched a bit anyway) but the build was proving to be tight to get the nipples in etc so Before I got too far into the wheel, I re did the right side with 260mm spokes.
So, spokes with the elbows on the inside are protruding through the nipple by about 2mm, the ones with the elbows on the outside only 1mm.
I'm not happy with the amount of spoke thread poking beyond the nipple (into the rim) so I am now removing the 260mm spokes and putting in 258 as originally planned.
All is well but, the spokes with the elbows on the outside of the hub don't make it through the nipple and stay inside by about 1mm below the screw driver slot.
So, what's best for the wheel, mix 258 and 260 on the same side to get the best nipple /spoke interface or stick to one spoke length and accept half the spokes on one side don't make it to the end of the nipple.
Sorry if this is a bit anal