Interesting question about complacency. Hard for me to speak objectively on this since I'm too close to it to be unbiased, but I'll try. I actually think the level of acceptable risk is gradually dropping. Each time something goes wrong, we add procedures. It's much easier to add rules than to remove them.

I do think the risk tolerance of individuals on the project does tend to gradually increase with experience, but we have fairly high turnover. It's common for MSL roles to have a year or more of training before certification during which you spend a lot of time focusing on what can go wrong, so new people definitely trend cautious.