always leave 15-20% of your portfolio in USDT simply for the reason that dips happen at least twice per month. Being able to buy the dip allows you to get out of the hole quicker, is better for your emotions, and though there are too many possibilities to quantify, I think over time your profits will be just as good. The only other viable strategy in crypto is to just buy and hold. It's alot less work.
What you have mentioned here are basic investment strategy as no one invest everything they have and they hold the reserve to invest when the market goes down especially when you are investment when the market is high. Most of the investors in the cryptocurrency market follow the buy and hold method as it is less risky and less stressful especially because of the high volatility.
The other major thing you need to follow is never use stop loss with a huge margin and the prime example was two days ago when the market had a good correction and anyone used the stop loss function might have liquidated their asset and then all of a sudden the market recovered and you might miss investing in it again.