Actually it is 25 flights, not 'exercises':
"The Supervisory Restriction can be removed on the recommendation of the supervising FI(A) once the applicant has at least 100 hours flight instruction and, in addition, has supervised at least 25 student solo flights.
It should be noted that supervision of a students PPL(A) qualifying cross country flight is counted as one flight only.
Approval of first solo flights by day or night and first solo
navigation flights by day or night are excluded."
But authorise a student for 3 circuits, come in for a cup of tea, then another 3 circuits, then lunch, then another 3, another cup of tea, then another 3 would, of course, be entirely OK?
So, if, as the Belgrano inmates would have it, the qualifying cross-country is a single flight (?), then it should be logged from the time at which the a/c first moved under its own power with the intention of becoming airborne until the time it completed its normal taxying after landing?
A flight is a flight is a flight. When I authorise Q X-Cs, I insist hat the student phones in from the intermediate aerodromes and has updated himself on weather, hazards etc, before the next leg is authorised. The next flight, that is!