Kevin
You can't compare across leagues because there are too many variables that affect overall race time. Weather conditions, temperature, tyre rules on/off, refuelling on/off all contribute to race speed.
You race 75% distance, no refuelling with tyre rules on. When you raced in Italy on 30th Jan the wining time was 50:03.533. By coincidence the league in which I compete has the same race distance and rules, our winning time in Italy on 14th Feb. was 49:32.138, over 30 seconds faster for a 38 lap race!
Does this make our league better than yours? Of course it doesn't, your time was set in the first race of the season with low design whereas ours was race number 8 so would have had at least 200 extra design points.
If your suggestion was implemented, by and large the fastest time would be set by a team competing in the last race of a 22 race season with ideal weather conditions. Anyone who competes in a 15 race season could never hope to get near the same time even if they ran the same race distance and rules.
I see, it would be quite hard to note all the variations, but i think it would be enough if there would be only for every league settings, and we could compzre us at the end of every season. (the fastest lap is the same)