I think it depends on the realistic financial situation of a person in some countries, or wealth class.So one part cannot be 25% in current day and age for most people.
The first part which includes eating, housing, donations etc, I doubt most of the world can make it to 25% of their monthy income.
Invest in work means basically getting the tools for the business, a farmer can upgrade their cart if broken, etc. The basics of capitalism, investing the capital into the business. For service workers it can be investment in night class for skills upgrade, or AI credits to help make the work faster.
For actual stock market investments, I am not an expert, and it seems more like gambling if one aims to buy low, sell high, but seems safer if one just wants to aim for dividen payouts, but it requires substantial amount of investment for the dividen to be livable. Also, one should screen for companies that does right livelihood for this investment (that means no KFC or Mcdonalds), and if possible not to invest in fossil fuel companies, or whatever social justice thing you’re pursuing.
Kept for times of trouble can be like during unemployment period, global economic recession, pandemic lockdown, climate change induced disaster etc.
It would be a good wake up call for people in the world to realize that ancient Indians are not actually poor when they can afford to spend only 25% of their income on not just survival, but also enjoyment, and including donations.
Edit add on:
When I was recently graduated from University, I had about $50,000 Singapore dollar debt, and I use close to half of my salary to pay it off. Got rid of it within 4 years+. University loan can be considered as a form of work investment, just paid backwards. I did had to use more than 25% of my salary to cover the rent, food etc.