When I was on the CM team I designed four Battle Of Britain FSO events, usually during the summer. When the "FuelBurnRateMult" setting was altered from it's FSO standard of 1.0, there were bitter complaints. Most of those were along the lines of "it's not fun". As it happens, the BOB maps we have are scaled to the real world at 1:1, so the FBRM setting of 1.0 is accurate.
The objective of FSO has been to provide an "even-ish" setup with both the high probability of contact (i.e., required targets) and historical flavor. It has not been historical re-enactment.
I think FSO is still the best thing in the game.
The 10 minutes over London story is a shibboleth.
It was originally rolled out to something of the form "30 minutes fighting time over Southern England and 10 minutes fighting time over London". I have never seen a single reference source that has had the backing of any actual research, scientific or just practical testing.
It is more of an unknown nonsense that is just about the first thing thrown out in any high school student's essay on the Battle of Britain.
There are so many factors that involve themselves in real life situations that to make such a "rule" would be untenable. A couple worth thinking about:
The form up time required for large formations in 1940 is significantly different to today. Whilst the Germans actually had superior radar at the time (another shibboleth - only the British had radar) they didn't have the organisation behind the technology to gain great advantage from it. Much fuel and time was used in just finding who you were supposed to escort at the right place and at the right time. Both sides spent the war trying to solve those problems and never truly achieved success.
Tactical considerations were paramount. If a 109 was to fly direct to London and conduct a leisure flight there before returning to the French coast it could spend a wonderful afternoon sight-seeing.
It only takes a 109 about 4 and a half minutes to cross the Channel under operational conditions. Things were different in the mass daytime attacks in August 1940. It wasn't so simple at all.
If a 109 had to climb over France, find its own wing, take up its position, intercept its bomber group and then weave back and forward above them in close escort, then it used up most of its time/fuel in those mundane tasks and not fighting.
It wasn't one-sided either. The Allies may have had a fighter that could fly to Berlin and back but they were still forced to send in relief waves as the escorts burned up their fuel long before they got there.
Believe it or not, the same still happens today.
All that said, I would reckon there weren't many Axis single-engine fighters that spent more than 10 minutes fighting over London in this last frame.