As for your fuel questions it's simply a function of track time, not really sessions.
I'm not as think as you drunk I am. Obviously we're talking laps rather than sessions. But my simple mind has these sessions at roughly the same duration. I was thinking 6 sessions at 25 minutes each is several more laps than 4 sessions at 30 minutes each.
On the free day I ran six sessions which turned out to be 38 laps plus an in and an out for each session or 50 times around. Sunday was 40 laps plus an in and an out for each or 48 times around.
I surprise myself that I continue to set a faster lap each track day. This time I knocked another second off my best time on the cheapo street tires, to 2:19.5.