the point to remember here is- the greater the PB the more extreme the stress on the body is and the greater the care must be going into the next comp or top speed session.
Of course, I favor less extreme measures done more often over time to yield overall higher results with less injuries (or, perhaps, because of less injuries).
But, if you have been stuck and training has not gone as planned and a big meet is upon you, this may be your answer.
Just make sure you are not in this situation in the first place because of a reliance on such extreme measures.