If you're in Canada you almost certainly want to diversify from Canadian indices. US markets have tended to outperform.
Indices can return >20% one year and -10% other years. I think OP is talking recently, not over 30 years. Over the long term indices like the S&P 500 tend to have a real return of 6-7% ...
That's the biggest problem I have with the recommendation to buy indices as if indices grow at >8% annually is an natural law.
Many (most) indices of countries in the world performed way less than 8%. US performed exceptionally well over almost a century so people are starting to take it as a natural law. If I buy US index, I'm still putting a directional bet on US stock market performing at an exceptional rate.
One can buy "all-in-one" index-of-index funds that have all US equities, all EU, etc. In Canada (which sub-thread stated with), see VEQT or XEQT (100% equities), VGRO/XGRO (80/20), VBAL/XBAL (60/40), VCNS/XCNS (40/60).
You can probably find an 'asset allocation' fund in most countries; e.g., in the US:
Indices can return >20% one year and -10% other years. I think OP is talking recently, not over 30 years. Over the long term indices like the S&P 500 tend to have a real return of 6-7% ...