You make that sound so easy. It's not. None of the maths of retirement planning is hard - but the actual decisions really kind of are.

For example, I've got 10% in corporate debt. Is that more or less risky than Equity? What's the distribution? What's the correlation? How does it compare with Reinsurance, or Property? Is property strongly correlated with the stock market at the tails, or is it a diversifying asset class? Does my passive fund hedge currency risk? Do I want it to? Is private equity a good or a bad idea? Do I want FTSE ALL or FTSE 100?

How about looking at risk appetite. What is the most time it could take for my retirement savings to recover to inflation adjusted parity after a crash (I feel like 15 years is the historical max, but it's a vague memory). Should I look at risk in terms of retirement income or retirement date? Do I expect Annuity rates to improve (e interest rates to go up) or should I mark to current rates for planning purposes.

I think about the amount of context that trustees for DB pension schemes needed to make investment decisions that were sound, and I can't help but wonder how we've ended up with individuals making these decisions on their own. I've long felt that outside of fees Diversified Growth Funds (Multi Asset Funds?) are a pretty good place to "inactively" manage retirement savings. After fees I'm less convinced. I suspect the Australian model might be closest to what I internally model as best?