20% of your income is meant for your savings, investments, and payments to reduce debt. What are the potential risks of having all three of these buckets belong in the same category?

We can never be sure if debt will remain at a steady level, or better, go down to zero, thus it could potentially reduce the amount left from the 20% which is also allotted for your savings, investments. Also, the amount needed for investment may suddenly rise depending on the economical situation of the country.