Complex sentence: Critics of HFT point out that while there are many reports of the positive outcomes, little is known about the mechanisms of action of HFT and what levels may be uFT delivery settings prescribed are largely empiric, with large variation of pressure produced by HFT between individuals.
Split into simpler sentences: Critics of HFT point out that while there are many reports of the positive outcomes, little is known about the mechanisms of action of HFT and what levels may be unsafe. There has been concern that HFT delivery settings prescribed are largely empiric, with large variation of pressure produced by HFT between individuals.