Got a question . . . a strategy I've been pondering . . .

I think you're right on. I read a Sam Snead quote somewhere (I believe it was Sam's quote) where he basically asserted that someone could legitimately play bogey golf or better by becoming proficient with a club to the 150 yard distance, and he mentioned a scenario just like yours with a 450 yard par 5. 

My only concern with what you're describing is hitting 100 yard approach shots with a 7 iron, which might not give you the loft or spin you need to stop on a tight green. But I'm guessing you're probably not that bad a slicer with your scoring clubs anyway, as the loft of those clubs typically causes more back spin than side spin. 

I help coach a JV golf team, I can score as well carrying a 4 wood an 53 wedge and a putter  as I can with my full bag..some days, I shoot better with just the 3 clubs..there are holes where the wedge clearly isnt enough.....but I can find it..and usually can scramble in those situations.

This is a pretty good post OP. Course management is one of things I going to work on next.
 

I guess it all depends on the purpose of your round. If you want to score as low as possible in a given round then you should absolutely do the things you are talking about. But if you are looking to improve then I fear this might be a hindrance to that. I am not saying course mgmt isn't a sound goal as I work on that constantly but there is a difference between putting driver away and hitting 3W or lesser and hitting a 3/4 5 iron 3 times. Hitting balls on the range is not the same as hitting them on the course and you need to put your practice to the test sometimes and get comfortable with it.

Anyway, I guess my point is that mathematically you are on the right track although you are talking best case of course so just remember that there will always be mistakes. Just don't always make lowest score the goal (call it a practice round for example). Sometimes you have to hit shots you are not comfortable with to improve.

My 2cents

Course strategy is key......... keeping the ball in play is a must.    On the other hand pitching 5-irons 150yds might not be a long term solution.   At some point, you'll need to swing at 80% and play an aggressive shot with each club to get to the next level.   The key is to play the correct club for the shot......not necessarily hitting a chippy/pitch 5-iron.     You are thinking in the right direction when it comes to course strategy............

One of the things I have found extremely helpful by playing a course you know by heart, is that you can play it any way you like. Meaning, that if you wanted, you could take a 9-iron and play with it the entire round with only that club because you know where the put the ball on a given hole.  You might not score well, but it won't be as bad as if you've played a new course.  I have played a 6700yd course that I know very well without using my driver, 3-wood, and 4-hybrid, making my longest club a 4-iron (~220yds off the tee), and I ended up shooting 5 over.  It was great practice with my longer irons, but its not something I could use to score low.  But it did teach me a great lesson, which I use all the time at every course i play, which I feel you may get to.  Course management for me off the tee, is putting the ball 150yds out from the green every time off the tee.  Obviously, only for par-4s, but if its 460yds, I'll use a driver. If it's 350yds, I'll use a 6-iron, because it'll put me at around 150yds which I KNOW I can hit the green with the highest percentage in that yardage range.  What I'm getting at is that you can go ahead and play a whole round using 1 club off the tee to fix it and find different ways of playing a course. But to score low, you must find the balance between each of your longer clubs regardless of what the length of a hole is and use the shorter ones you trust to get you on the green with the best chance.  Sounds easy, but once you start hitting a particular club well off the tee, you'll want to keep using it, but may bring more danger into play and start missing greens if you end at a distance you're not as comfortable with.