Just out of curiosity snoopdog ... how far into your PhD are you (or have you completed)?

un-needed experiments??? what do you mean?

The national average of completing PhD is 4 years, BTW

Well, I had 3 years of postgrad research lab experience before embarking on my PhD and it still took me 4 yrs. I worked like a dog throughout and had fantastic supervision - sometimes delays are unavoidable!

I took 4 years as well and had 2 masters degrees behind me. Getting done in 3 years is (I think) the exception rather than the rule.
If you can do this, great, but it's more likely it will take longer. I had to go through ethics committess and spent virtually most of my first year sorting that out despite good supervision. And I knew some of the the clinicians/NHS ethics committee members!

I have seen so many people say they will complete in two years and none of them have yet - don't think I've seen anyone complete in less than 3.5 years

i was at this meeting in uni and at my uni you are not allowed to hand in - whether you have completed or not - when you have like 8 months to go. the earliest you can hand in is about two months before the two years are over.