Blimey
Can you define what ‘it’ is? If you mean practice dropping bombs from the last century in a contested air environment then yes low level is good. But ‘it’ doesn’t work that way any more. The role of modern fast jets is not one that happens at medium level just because it’s easier. It’s done at medium level because that is where the tactics and the weapons dictate that they can be most effective and survivable. Practicing their modern role at low level would be pointless.
During flying training there is definite value for low level as a training tool and a way of assessing and developing mental capacity. That doesn’t mean it will ever have any application in a modern conflict.
There are of course times that certain A-G weapons may need to released with a visual line of sight which may require a FJ to get below the cloud which is why some LL training is still done, but it is nothing like the old fashioned four ship 45/60 second splits from the good old days.
BV