At some clubs the instructors don't sign log books for each flight - this does seem unnecessary when each flight is written up in the student's records ... unless you're planning to start learning at a dodgy club that might go bust at any moment and continue your training elsewhere, of course, in which case access to your records might be difficult when you change clubs.
When I applied for my PPL my own log book differed from the club records ... my log book showed that I was 5 minutes short of the required instrument flying time, the club records showed that I had exactly the right amount of instrument flying time ... so clearly the club records must have been right and I corrected my log book to match
I do get my log book signed when I fly in strange places whilst on holiday - this is a requirement of my "home" club for proving currency, but in practice they take my word for the currencty and never look at the log book and I just collect these signatures and/or rubber stamps as souvenirs.