This is an area I've struggled to figure out over the last couple of years. My ideal situation is to find a 200 yard club (4 iron spot) and 225 yard club (hybrid/fairway wood) and then go maybe 3 wood and driver. I hate not having those two yardages for longer par 3's so I try to work that in.
I'm just trying to get usable results every time I pull a longer clubs. My ball striking with those clubs is bad enough right now to where the only goal is advancing the ball to within wedge or short iron distance.
The top of my bag includes Driver, 3H, 4H, 6i. While the driver has the potential for the most distance, good contact with the 3H will get similar distance as my average drive. Unfortunately, taking less clubs at the top of the bag does not result in a higher percentage of good contact. It's a hot mess and not the way the game is supposed to be played.
I started a thread on my potential acquisition of a 9 wood. It will fill a gap in my bag in the 185 yard carry range. I know for many that is a 6 iron but for me it is the top end of my bag as it sits between 5i and 5W.
It does depend on courses you play and frankly your skill level. I am expecting to hit or at least be close to greens from up to 210 yards out and need clubs in the 175-210 distance that I carry specific distances. In the old days those would run between 6i and 3i so it was a different issue.
The perfect example of the importance of gapping at the top of the bag came up yesterday.
190 yard par 3. Over water (downdraft). Elevated green. Big burn in front (about 12-15 feet elevation change). Significant wind against us. I learned a few years ago how to hit partial shots or step on it with every club in my bag. So, this gave me three options: step on it and draw the ball with a 3-hybrid, Hit a stock straight fairway metal, or take a bunch off with driver.
Most days I use my hybrid into this hole. But the wind was up and the pin was back requiring a tight draw. I would usually choose the fairway metal under these conditions. I'm generally really precise with that club, but today I was out of sync with that club. I went with driver and took a lot off knowing that I needed to land it short on the burn, letting it take some of the roll out. I executed the shot and was the only one on the green off the tee.
Now I know everyone's skill set is different. But the point is gapping at the top gives you the ability to maximize the possibility of getting the ball on the green or in an ideal position on the fairway. Both lead to lower scores.
Also people saying that I've got too much overlap at the top end of my bag... like a 7W and a 4H. The 4H is 21 degrees, the 7W is 22.5 degrees. The 7W is about 2-1/4" longer than my 4H. Let that sink in for a second. When I'm faced with a long second shot on a par 5 in the light rough and the ball is below my feet, I need nearly the same distance to reach the green. Which am I reaching for? The ball could even be on the fairway. I'm reaching for the 7W even in the light rough because of my tendency to either top the ball or dead pull the shot with the hybrid with the ball below my feet. The extra length that club and along with the loft gets the ball in the air. So there is no overlap. With the ball above my feet I'll use the 4H every time and choke down on it.