Just a quick poll/survey to see if we're causing ourselves problems ....

There's no answer to pick that applies to me so here's my experience:

Right after I bought my GS back in 2012 and I knew nothing about bikes, I had an issue (that I'm guessing was fuel starvation)... took it to a shop and they replaced the frame petcock.

Ever since then, I've had no problems with fuel starvation. I've done a couple years with an inline filter, some years (currently) without one... no problems either way. I replaced the fuel lines with generic from an auto parts store (I don't remember the size) ... no problems. Last year I swapped to OEM fuel lines and I love them. Still, no problems.

Short answer - no. The fuel lines are standard (whatever that is). I've never suffered from fuel starvation, so I have never had to play with them.

I have a 2006 with factory fuel lines. Never had a starvation problem even at prolonged 60-70mph highway travel. I've mentioned in several other threads over the years I had starvation problems on other bikes before due to the fuel cap vent being clogged. The vacuum line draws the gas into the carbs and the vent lets air in the tank to fill the void left by the gas. If your vent is clogged it crates a vacuum inside the thank greater than the vacuum line creates thus it can't suck anymore gas.

That being said I don't know what type, or even if, the GS has a tank vent. I Would imagine it does. My past bike has a spring loaded BB valve that got sucked open as the as gas was pulled from the tank. It was sticking and starving the bike of fuel. On a couple occasions I had to spray it with electronics cleaner and I was good to go.

your fuel starvation issues, if that's what is happening, is not because of the fuel line size.

most have replaced the fuel lines with 1/4" because 5/16" tends to leak, and there is no fuel starvation. Look elsewhere for the cause of your issue.