No you can't. Some in the PFA have been doing this apparently, but it is NOT acceptable; the CAA confirmed this recently.
A 'flight' is the time from the time at which an aeroplane starts taxying with the intention of taking-off until the time it stops taxying after completing a landing. If that's half an hour and you then have a cuppa and go back again, you have NOT completed the requirement. I agree that is plainly ridiculous, but we are talking JAA here....
However, that's thanks to the Eurocrats. For the NPPL , once the nonsense of the current temporary AIC (3/2004) has been superseded, we intend to phrase the re-validation (by experience) periodic training requirements to read:
“NPPL holders with valid SEP or SLMG aircraft ratings shall, within the 12 months preceding the expiry of the rating, complete flight training with an instructor of not less than 1 hour total flight time.”
But for the JAR-FCL SEP Class Rating, it must be one single flight of not less than 1 hour.