Still, I think 40 years starting from a count (Navarra is a kingdom!!) is very, very unlikely. As I said above, there are not enough claimants. Kingdoms shatter a lot, mopping up the remnants takes time. Furthermore it takes pretty long to take all those damn Republican cities around the Mediterranean. The HRE is the way to go as it is the realm most difficult to take out. But if you start inside the HRE as a one county count (this is the only really rewarding way to do it ^^) you have to spend 20-40 years to become emperor.
I also think you didn't read most of what I wrote as "tips & tricks".
To give an example:
I can conquer Pisa in 5 successive wars for 3 Duchies & 2 Counties (just example).
I would bring ~30k retinue-mercenary army with ships to Pisa's shores and unload them all on a County, assault-siege in a few days, embark, unload on neighboring County, assault-siege that one too.
(The lands I siege won't be the ones I claim btw)
When Pisa surrenders, I would start a war instantly and this time, I would unload ~4 x 7.5k army to 4 recently sieged Counties and assault them in ~5-6 days. (They would have zero garrison)
I would do this 4 times and the last time, I would claim the lands that I've been sieging all along.
And the whole operation would take a few months at most.
(I didn't know about this in the beginning, but used this on Seljuks..)
No months of marching, no army loss etc.
Aye, cheesy.. But plainly easy..