If you don't mind I think we need to clarify - what difference do you see or feel inside the house or is it just when you enter the attic? Are you in the attic a lot? If you are in there a lot there are better options, but if the fans help you then no worries.
But if you are hardly up there, and don't notice any issues downstairs then they should go.
If you do notice some issues then you might want to check how well sealed the attic is. Where do you feel the heat coming in? There are ways of insulating hatches, doors etc... without wasting money running fans.
If in doubt consider bringing in a local experienced energy auditor or contractor.
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