After serious thinking Chris Green wrote :
Yes, that's my experience too. Anything that's not easy to start has
something fundamentally wrong with it that needs fixing, not a squirt
of magic spray.

I agree - It can actually cause extra damage, by washing the film of
oil from the cylinder bores, so really its use ought to be for
emergencies only. I've kept a can in the boot for the past ten years,
just in case, but it is still unused.