What's the opportunity cost of waiting for a pullback (i.e loss profit potential). It's 2 sided equation here.
Probablity of determining trade direction x probability of correct entry x probability of stop placement x probability of target...
It's not that easy. Which is why I said the answer comes from detailed market knowledge, i.e., statistics of how your chosen market moves most of the time.
For example, if you look at index futures or ES, it will very rarely move say 20 points without a solid pullback. ES is a market that retraces a lot.
So, let's say you recognize a strong trend higher and the market moved 20 points. Will you enter there knowing that 80 % of the time that's about where it will start retracing and you are likely to buy a top?