There are a few posts out regarding this. Longer lines cater for more power so yes, either allowing you to use a smaller (and lighter, niftier kite) or maximising the power of a larger kite. I use only 3m line extensions so use 28m lines as I prefer only a subtle change in feel and I use regular lines which are a bit thick for that purpose. I can see why some are using up to 35m lines but they then use thin racing lines.

Longer lines make your kite less responsive. Can be a good thing when foiling but be aware of this. You also need a wider beach ;-) and you have more seaweed trying to bog you down if your kite hits the water in such conditions

Just out of interest what size kites are using and in what wind conditions I am 90 kilos and was out on 11 metre kite in less than 10 knots and found the kite almost too big and had to run on a lot of dpower and this was on standard line length

I am still at an early stage in progression however come from strapless surfboard experience.
20m lines were the only thing I would consider but now 27m lines for foiling works.
Benefits for me are:
- Smoother control
- Smaller kite to get up on board
- less chance of being over powered when up on the foil due to smaller kite
- all resulting in greater confidence

I happily use 36m (thin race) lines and a 5m kite. So much time to loop and play with the kite !

Plummet said..
i'm pretty boring. stock lines 25m.

Kite sizes for foiling
6-15 knots 12m chrono
10-16 10m edge
12-20 8m catalyst
18-25 6m reo
25+ 4m uno

I think there is sufficient evidence that boring works pretty well for you.