5K SIP. Long-term (15–20 years). Appetite - Aggressive. Help me decide

Planning to invest ₹5,000/month through SIPs for the next 15–20 years. I have an aggressive risk appetite and don't expect to need this money anytime soon.

This is the allocation I'm currently considering:

• 30% Nifty 50 Index Fund
• 30% Nifty Next 50 Index Fund
• 20% Mid Cap Index Fund
• 20% Small Cap Active Fund

Does this allocation look reasonable for a long investment horizon?

I've also often heard that only 2–3 funds are really necessary. In the future, I also plan to invest in US index funds once that becomes a viable option again. Would this make my portfolio unnecessarily diversified with too many funds?

I'd appreciate suggestions on:

• Whether you'd change the allocation.
• Whether you'd replace any of these funds (e.g., active vs. index).
• Any changes you'd make and the reasoning behind them.