Anthony
The 0.3 variation that I mentioned is rare, in my training it must have only happened 3 times, but it happens. Now 0.1 and 0.2 is not that uncommon, not that it is bad, it is good to have a greater challenge for the races. Laps with the same tire compound have a smaller variation, but we normally use 2 and even 3 compounds.
Example: If I want to start on soft tires, put on medium tires during the race and finish on hard tires I would have difficulty having accurate data for the 3 compounds with just 5 laps. With 10 I would be able to do 3/4 laps with each compound and go to the race more safely.
It is "Push Level" that influences the fuel consumption, it is not directly related to the tyre compound. The tyre compound only indirectly affects fuel consumption because during the race the softer compounds require lower PL (hence lower fuel consumption) and obviously the opposite for harder compounds. Clearly temperature also plays a huge part because again, if it is hot you will use lower push to prevent the tyres overheating.
Having 10 laps will not give you any better information than what you get for 5. If you're worried about 1 lap out of 5 having a variance of 0.1 litres then take the average of the five laps.
A better approach is to make notes of fuel consumption and push levels after a race and use this information to inform you at future races at the same circuit. Most hardcore managers do not take any notice of practice lap data when determining tyre strategy or fuel requirements.
