Of course, I remind everyone of the "sole manipulator" part of the reg.
As a flight instructor of 50+ years, MOST new aircraft checkouts are NOT 100% "sole manipulator",
Especially tailwheel. A conscientious flight instructor will only allow logging PIC time when, in fact, the pilot is "sole manipulator". Especially during T.O. & landing practice.
It isn't logical to expect 100% sole manipulator time during ANY checkout- much less tailwheel .. .
Yeah there's some points where you wont be the "sole manipulator" especially in a tailwheel where ground maneuvers have additional risks and wheel landings are the opposite of what tricylce geared pilots are used to but I agree with mkosmo that you'd be splitting hairs.
That's be like flying for 3.5 hours being under the hood from just after takeoff and down to minimums on the approach and deciding to log 3.14159 as your SIM instrument time because your start/taxi/runup/takeoff and your landing/taxi/shutdown time was 15 minutes and the instructor needed to take over to put you in an unusual attitude for recovery or to steer clear of traffc for another 6.5 minutes. Perhaps its more accurate but is it likely to be an issue if you logged it, say 3.2 or even 3.3 instead of 3.14159 or 3.1? No
A tailwheel is a particularly bad example too... Generally speaking, a pilot getting a new insurance checkout or high-performance or complex or high altitude aircraft endorsement is likely to be the sole manipulator of the controls through the entire flight. Is there really any reason a current and proficient C172 pilot would need the instructor to take over and/or be on the controls when getting signed off for a C182? In theory they shouldnt.
Also, once you have the log book entries to meet minimum requirements for a particular rating, your log book becomes largely memorabilia and a scrap book than anything else. Technically the FAA requires you to keep the log but if you never log another flight again except your last BFR, last instrument approach and if you have passengers, your last 3 landings in 90 days (or nights) then whose to say you haven't flown any other flights in that windows? Your're still legal and current for all of it and its not like its going to matter that you didnt log 12 other flights you recently flew.
In the end the FAA looks at log books for 3 reasons: 1) Ratings, 2) Ramp or other check looking for currency and 3) if you crash the plane they'll want to review your log (if it is available and/or can be found in the mess) to ascertain total time in type, condition and x number of months to see how time might have played a factor in your screw up that ended with CFITS.
Now as an ATP, your log book takes on a different importance since it also document hours flown in a given week and has other considerations that makes the general accuracy and up-to-date status of an ATP's log book more important than for a regular private pilot.
I do know plenty of private pilots (myself sometimes included) who dont log flights right away and log them every 2 or 3 times out.