There is no real magic number here. Let me put it like this.
Inflation only a short term measure of devaluation based on consumer goods and services NOT on assets. Usually, asset prices fluctuate way more than the average consumer items (different industries at different times though).
So, when doing an investment we expect to park our capital in an industry or a commodity where our gains far exceed the average price increases of assets.
In Sri Lanka, Real estate, Vehicles, Equities (back in the days) are popular examples.
These pension schemes or investment schemes are extremely poor performers compared to the above investments. When you finally get your return you most likely to find that you can't buy much stuff with that as you thought before.
The dirty trick these companies are playing here is they use average persons instincts to their advantage. Normally when someone hear the amount they think it is BIG! but it is NOT when you get it 30 years later!
I'm not saying it as complete trash. It may fit with you depending on your circumstances if you like to have some cash in the future but to me it does not sound like and Investment. This is over bragged and marketed for sure.