I have not experimented just followed their advice, so I don’t know the impact first hand, here’s what they say:
‘The weight distribution of the component can also be taken into account. If for example the component is heaviest at the back, then it is common to use 3 isolators with 2 positioned at the back corners and 1 positioned front/center.’
I have two at the front and one at the back, but again I have not experimented.