conical valve springs(non-KTM related)

i was cruzing the web looking at stuff and stumbled across this site. http://www.wmr1.com/tips.htm they have the cure for broken valve springs. Been a long time since physics for me. Can anyone confirm or deflate these claims of the failure mechanism of most springs? Is the conical spring the anser? I see KTM used them in at least one application where they were breaking valve springs.

Just wondering. We're off to the 150F's soon.