So thinking about your pool at 17,000 gallons, that means a decent size, but not huge. I see 7 returns as overkill. I am going to suggest something that might need some group input on the flaws with this.
Two immediate thoughts
1 - I would look at the flow in the pool, and possibly consider capping off 2 to 3 returns to bring better flow to the pool overall, by directing the limited low speed flow to the jets that directly influence overall skimming in the pool
2 - I worry about capping them off trapping in water that does not get circulated, creating a breading ground for algae to bloom and spread out to the pool
So I would possibly put on caps, but drill a few holes of small diameter (such as 1/8") in the side wall of the cap. This would allow a small amount of flow, and send the flow directly down the side wall of the pool, which will aid in overall circulation of the pool. Or you coudl put a hole on the bottom, directing flow straight down to the bottom, which woudl force colder water up to the top and help even water temps. I feel like these concepts would be an overall improvement in your pool flow, and make sure that all returns had at least some flow. Thoughts from the masses on this idea?