Hey Vish,
Everyone's situation is different. Although the top 20 has proven to outperform time and time again, there are times when it is heavily weighted towards certain industries. Case in point, since gold stocks have been on the rise and analyst estimates are rising, they are currently dominating the top stocks.
We always recommend having a well balanced portfolio, and investing in say 7 gold stocks is a very risky proposition. Although unlikely in this environment, if the price of gold falls off a cliff then holding 7 gold stocks could lead to big losses.
Furthermore, you also need to do your due diligence. Case in point, AC is in our Top 20, but we would not rush out and buy this stock. Considerable headwinds remain and in fact, the company does not expect to return to pre-covid 19 revenue until 2022. That being said, you may have very high risk profile and find the risk/reward acceptable.
All this to say, there is no 'right' way to distribute weightings and it will be dependent on the investor's risk profile and financial situation. However, we do recommend you remain diversified (not all your eggs in one basket) and do your due diligence to ensure you are comfortable with your investments.
Finally, a side note - keep trading fees in mind. I always try and keep my fees below 1%. This means that on a trade that costs 9.99 - at minimum I would have to deploy $1K. In other words, I would not dump that into 20 positions as I'd incur higher fees. At maximum I would spread it out across 10 stocks. Might not seem like much, but over the long term they make a difference and eat into profitability.
Mat