Stopping the plants at around five or six trusses makes the crop 'finite', but occasionally, if I see a plant belting away, I let it go on a bit, maybe to seven trusses in case we have a decent autumn.
I guess the issue is to have enough plants to make what fruit you need/want, then have a bonus if they carry on well into the autumn, which they sometimes do.
This year, I've actually trimmed them all back to five or even four trusses, as the light was just not good enough for the crop we needed to ripen, but it's a risky call, especially when there is so much blight about...
But to answer your question, a chum lets hers go right up to November, as there will usually be a few toms spare, but there again, she has a huge greenhouse!
