If you absolutely want a 99+% chance it would last the first 90 days, then really the chances are that's it's going to last a lot longer. I actually don't think it's a typical quality tradeoff. Because you have to meet a high initial reliability, you end up with higher probability of hitting a endurance beyond your minimal requirement for the device.
I'm also guessing w.r.t the structures, you'll have to build to withstand a worst case environment during the launch and landing. Once you've survived those you're "overbuilt" with respect to rolling around the surface, but the strength was needed to survive getting there.
I'm also guessing w.r.t the structures, you'll have to build to withstand a worst case environment during the launch and landing. Once you've survived those you're "overbuilt" with respect to rolling around the surface, but the strength was needed to survive getting there.