I'd agree but would amend that with saying that if you NEED to flush you will definitely know it. (Talking about flushing excess nutes mid-grow due to overfeed and salt locking out nute uptake... also often referred to as "leeching" rather than flushing to avoid confusion with the end-of-grow flushes many do.)
When a plant needs to be leeched/flushed of salt build up in the medium, you will notice it won't uptake the fluids you add, regardless of whether it's nutes or a regular watering... it will wilt heavily, but that wilt cannot be cured by watering. Further, the medium will take longer than usual to dry up (because the plant is not taking the salty water) and while it might seem like you overwatered, it will only wilt more and more even when you leave it be to dry. If you see this pattern developing, flush immediately with 3x the container volume of clean, tepid, ph balanced water.