Essentially I don't think it matters a great deal.
The issue is heads down. If you are spending time reading checklist items such that the aircraft wanders from the heading/alt/speed then you are not managing the flight efficiently. However if you try and memorise the checklist such that you miss vital items then again flight performance will suffer.
The examiner will draw an overall view of you from the moment the flight start with pax briefings etc.
I would however always operate the aircraft according to the phase of flight as others have suggested. On the ground you have time to follow the checklist but always try and show that you have read the flight manual ( during the idle check show you know the limits).
During critical phases of flight I would perhaps suggest that you memorise the checks but always, always, always reference the checklist.
I would however avoid doing ice checks silently, if the examiner misses them he may think you have forgotten. Do lots at the start of the flight and hopefully he will ask you to stop.
Best of luck with the test my friend.