Under JAA there was never any requirement to sign the entry, it was just something the CAA invented in their efforts to 'gold plate' the 'training flight of at least 1 hour' into a Test.
Under EASA,
all training flights have to be countersigned by the Instructor, whatever their purpose, or they don't count.
MJ
Ps. I can't, for the moment, remember where this is stated, but I'll try to find it and come back with the reference, unless someone beats me to it!
MJ