The advice/rule of thumb I've heard a lot is that you want your age in percent for bonds/safe stuff. So If you're 44, 44% not in stocks basically. I've got a lot of investments other than my 401k that are 100% stock/index mutual funds, but my 401k is one of those ones that manages based on your goal for retirement year from Fidelity and it's breakdown of stocks/bonds actually does mirror pretty closely to that rule of thumb.
Personally I don't follow that. Overall I'm way less than than that rule of thumb across all of my investments. I did buy a big drop of those > 7% I-series bonds from the treasury earlier this year. I might be closer if you count cash sitting in a savings account but still not the ROT percentage.