Mine are quite effective: some pilots can score 3 kills+ per night if the Force is with them.
I progamme a NI sortie to the airfield of interest about 90/120mins after bomber T/o time (dependent upon range). Altitude approx 17,500ft. "Follow" at about 30 min. intervals for approx 2 hrs. I usually alternate Mossie/Beau.
Rarely, if ever, do I integrate them with the Bomber stream.
109s I find hard to kill, however, so I concentrate on the twin-engined NJG bases.
The Nazis entered this war under the rather childish delusion that they were going to bomb everyone else, and nobody was going to bomb them. They sowed the wind, and now they are going to reap the whirlwind.