How much portion of take-home salary should a person invest in SIP?

Many investors follow 50-30-20 rule for their monthly budgeting. It means that 50% of their take-home pay goes towards needs, 30% towards wants and remaining towards savings and investments. Going by this rule, someone with take-home pay of ₹40,000 should invest around ₹8,000 for their savings and investments. The allocation of the money towards assets depends on investor's risk appetite.