People need to stop using "Only 1% of people do this" and "It takes a long time to copy a base!" as reasons to eliminate the 24h cooldown. Changing this would create a bad atmosphere for competitive arranged wars. For example, we could have a TH10 get 2 stars on the enemy TH10 because he works during the day, whereas an enemy TH10 could 3 star ours because he is a student on summer break and had literally the entire day to repeat the attack. This ruins the competitive atmosphere of the war entirely.
Eliminating the 24h cooldown will bring back that feeling. "That TH10 attack was so clean, wonder how many times he practiced it beforehand." Obviously this situation isn't as bad as the times of modding accusations, but it is still a huge detriment to having competitive wars. Wars should be decided by skill - the skill involved in dissecting a base for weaknesses, the skill involved in formulating a plan of attack to exploit the weakness, and the skill involved in executing that plan correctly while reacting/adjusting to any traps/cc units - which the current cooldown is designed to promote.
No one can know for sure if only "1%" of people will do this; that number is completely made up by you. People could just recreate a portion of the base to test out specific things (and spam other buildings in corners), which makes it very easy/accessible for even casual players to do this. No one knows yet the extent of how much this feature will be abused if this change is made. Modding started off the same way, being limited to a very small minority of players. No one batted an eye because "it's just a small percentage, who cares?" and look how widespread of an issue it became before SuperCell did anything. It is not unreasonable to expect that as time passes, more people will start to use this to sandbox attacks for the same reason that more people started using mods. "The enemy clan does it, so I'm going to do it too."
Notice that this change would also impede SuperCell from making QoL base editing changes. For example, if the 24h cooldown is removed, it would be a bad idea for SuperCell to release a base building update that allowed people to copy/paste war bases, as then everyone would abuse friendly challenges due to the convenience of it. Again this is just an example, but why even open the door to exploits/future potential problems like this?
Take a minute to think deductively about not only about the short-term consequences, but also about the implications for this game's future. Would removing the cooldown ruin the game in a week? Of course not, but what about a year from now?