I find easier to sail in overpowerd condition when lines are close together than 20cm apart.It is easier to open sail ,because boom pivot around one point.

What are your experience?

I like them further apart about 30cm, imo helps to oversheet and stability in the rig. A lot of people now seem to sail with them very close together though - seems to be the cool thing to do

Shortboarding 38 years, 30 cm seems fine.

I've always had them my hand span apart which is about 24cm, then 2 weeks ago I moved the front one about 4cm back so they are closer together and I'm finding it it a lot better. It wasn't a intentional adjustment the front just slid back in a crash and I didn't notice at first until I was trying to work out why one tack felt better than the other?
good things come from wipeouts

Don't follow 'fashion'! Just do what works and feels best for you. For free ride and slalom, having 30+cm apart gives you more stability and control because you can slide the hook back and forward a bit to help balance gusts and lulls. The most important bit is to get the line fixing points in the best place for overall balance so neither arm is being overworked and you can fully load the sail without arm strain.

This works for me:

I'm liking the floppy harness lines.