Nope. There is a slight amount of extra drag over the guides but it isn't as much as you would think.

 Depends on the rod.

A 15 foot surf rod at 90 degrees will have more friction than a 5 foot jigging rod at 45 degrees

 I'm struggling to wrap my head around the question..  A 30lb rod should be used with 30lb line and the drag should be set at 10lb... 

That's not the failure point of the rod or reel (don't max drag a reel).  The rod will just be at its efficient curve at that point but will handle a fair bit more usually...  

The reel should be used within its manufactures guidelines (pe or lb line capacity will be on the spool)..  Even high gear has limits (someone complained on fb the other day that a 4500 saltiga died while using pe 6 line..  It's not a pe6 reel even if it can put down 15kg of drag) 

Yes the rod does take some load ... but I would suggest it is closer to the truth saying the REEL generally takes about 66% or more (depends on many factors like rod length and stiffness, line thickness, drag settings, etc ...)

For example, if I put a set of scales on the end of the line of one of my rods and pull the line straight off the reel (ie. straight rod/no resistance) I get about 2kg of reel drag on the scales. When in a boat rod holder and pulled straight down (ie. as would likely happen bottom bouncing), then due to the extra resistance from the rod curvature, the scales register about 3kg. That is, under load, with 3kg of pressure applied to the tip, about 2kg of pressure is loaded down on the reel (66% of the load on to the reel). The other 1kg of pressure is stored in the rod's resistance. (NB: it took about 2.5kg to pull line off at something in between the two, as would likely happen shore based fishing).

If you choose to fish with 30lb line, then it may actually break at about 20lb at the knot (or weakest point). To be safe, it stands to reason to put no more than about half of that pressure on the line ... therefore, 30lb line should not be fished with anything greater than about 10lb of pressure (about a third). Likewise, if a rod is weighted at 30lb, then you want to avoid breaking the thing, so about 10-15lb of pressure on the rod. If you have a reel capable of 5kg drag, then unless you want to shorten the lifespan of your reel, you should not exceed about 3kg of drag on that reel.
So even though I may disagree with your 66% load on the rod theory, your combination of 5kg/30lb/30lb is not far off what I would subscribe to (assuming the 5kg drag is the theoretical maximum but in practice 3kg of less would be used).

For what it's worth, I run the following on my boat rod bottom bouncing, about 2kg/4lb drag (has a maximum of 17lb at strike), 80lb braid and rod 80lb.
And on standup game rod, I run about 4kg/9lb drag (or less, has a maximum of 25lb at strike), 30lb mono, rod 30lb.

It comes down to horses for courses and how you want to play/fight/dominate your catch.

 Interesting, 

I think the consensus is... Not much and depends on the rod.

I'm also curious how much drag (measured) the rest of you are actually running on your day to day outfits and if you know what your line's actual breaking strain on the knot is (again measured)? 
At 2kg of drag, with the reel at strike, when I want to manually check the drag (throughout the day), I can only just pull line off by hand.
If I put the reel in to overstrike, that is over 5kg of drag and I can't pull line off by hand.
I have tested what it is like at 3kg and under load, that has my arm shaking and legs wobbling trying to keep balance.
I want to fish comfortably and that 80lb rod and line is still sensitive enough to feel whiting bites but gives me the confidence to catch 20kg+ fish (it has accounted for 7foot+ 100kg+ bronzie to the boat and conseratively more than 100 Dhuies ... admittedly, not all 50cm+).

Ahh wait up..  What's your actual measured drag at strike?? I think your measuring the first little push of the lever as your "set drag"..  Your strike drag should be the measurement 

 Think there is a problem with the way you are measuring your drags. I do a lot of line class mono fishing so my drags are regularly checked with drag scales. 3kg is roughly equivalent to what I would run on a 10kg outfit. Something I'm comfortable giving 8 year olds to catch their first billfish. My 11 year old handles 5kg of strike drag on a 15kg combo no problem.

I have been testing what I have been posting.

If I say 3kg of drag, to me that means if I hold the reel in my hand, tie 3kg of drag to the end of the line, then NO line drag will occur. If I add 100g more to the weight and I see the first sign of drag, then that is 3kg of drag. I have also been checking my results with digital scales.

I also did a quick search on the web for drag settings and quickly found two game fishing articles suggesting 3-5kg of drag for Sailfishing and 10% of the weight of the expected fish.

Last year I caught a 20kg+ Wahoo on 4kg drag on my standup game gear. It took about 1 or 2 minutes to get to the boat.

I can do 10 reps of 20kg bicep dumbell curls easier than lifting (with one lever arm) 5kg tied to the end of the rod. Go and tie 5kg to the end of your combo and see just how easy you manage to do 10 lifts with just your lever arm.

Given my research and testing, I doubt that many people have a good understanding and respect of just how much pressure 5kg of drag is.