No they're not!
But if you really can't consider sending someone solo with whom you have never flown, you're going to be of little use to any flying club once your 'R' is removed.
Supervision is a matter of considering all aspects of the intended flight, not merely of assessing the pilot's handling skills. That's what the supervising FI is looking for when listening to the brief you give to the student and the manner of your supervision.
But the 25 solo sign-offs is utterly pointless. The CAA will only allow 1 for a 3 x 2 hour qualifying cross-country exercise (even though each leg is, by definition, a separate flight), but if you authorised the same pilot for 3 separate solo GH trips on the same day, that would be fine...
Or 25 individual flights of 1 circuit each?