Is Short strangle of deep OTM a good strategy for great returns?

No, because the premiums would have been already very low and theta decay will also be very less.

Definitely a good intraday strategy for the weekly index options, provided 

1. Options strikes, Premium to be sold, Entry Time, Exit Time and SL are pre decided
2. Courage and discipline to follow the plan 
3. Follow the same strategy for the whole week

Based on personal experience, 

1. Win rate of the strategy is 65%
2. Expected weekly returns can be in the range of 0.20% to 1.50% including taxes and brokerage. Similarly losses could be in the range of -0.05% to -0.50%.

New trader should try out with paper trading for a month to create the required mindset, before jumping into with real trades.  

Short strangle deep OTM gives low returns due to low premiums. Also, it is an unlimited risk strategy. You never know the put side can go ITM. Remember 23-March-2020 corona crash. So, better to do iron condor instead of short strangle. At least the risk is limited plus you needn't sell deep OTM. Besides, you can deploy a hedged strategy with much lower margin.