From experience at my airline, it's a bit of a mixed bag whether or not the captain (tiller only on left on my aircraft type) follows the marshaller guidance. A lot seem to disregard directional instructions, but only obey the stop signal when it is given.
Having said that, I recently flew to one of the airports on our network where the particular parking positions at which we park are some of the tightest, in terms of manoeuvre space and turn radius. I was flying with a captain who vehemently follows marshaller guidance, on this last occasion. As we were approaching the stand to make a right turn in, captain asked me to advise him when the marshaller started making his signal to turn, as they would normally be out of his view before the main gear would approach the extended centreline. The marshaller, very early, began his signal to turn and the captain obeyed and initiated his turn, while I called clear right ensuring that no obstacles/equipment were in our way. It was fairly obvious that the turn signal was made too early but the instructions were dutifully followed nonetheless (and who am I to argue with that). When we came to a stop we were at least 30 degrees offset from being centrally aligned. Probably the worst marshalling/parking I've experienced.
At the end of the busy turnround, just before pushback, I noticed 2 of the ground crew had taken out their phones and appeared to be taking a photo of something on our aircraft. I flagged this to the captain, in order we ask to make sure that everything was ok. The captain asked over the headset (to the same man who had marshalled us in), if something was the matter and if the aircraft was ok. He replied, red-faced and chuckling, saying he doesn't know what's wrong with them (his colleagues) and they were just taking photo evidence of his marshalling. All good, as long as nothing wrong with the aircraft! No doubt those photos ended up in the some whatsapp group or similar, that day. I imagine that the marshaller will slightly delay his turn signals in future, in order to avoid a repeat scenario and further banter from his mates. Positive learning and all that! 😄