As you said, wunderbar is also rather easy to damage the blade, so I usually changed it after 1-2 times.
Eh? I have used the Wunderbar with a Wizamet for all 6 shaves in a week with no damage to the blade or to me. I've used a Polsilver Stainless for the same duration, and given the quality of those blades, could have gone into the following week but swapped it out from habit. I have never damaged any blade in the WB, or any other razor for that matter.