What I said makes perfect sense. It is very basic level statistics/probability.
Each time you put in one attack on every base that hasn't yet been tripled, 50% of what is left will be tripled this time. You never reach the point where every base has been tripled.
Obviously when there are odd numbers, sometimes it'll be up, sometimes down, and sometimes this will end up with every base tripled, but equally it often won't.
All that is just on the basis of random 50% chance on each attack. Obviously, real clash isn't that random, and that will have an effect.
You have to take account of the fact that the ones that don't get tripled the first time are likely to be the harder bases, so probably less than 50% the second time. You also have to take account of knowledge gained on first attack, which will increase the rate, but probably not enough to take it above the 50% again.
But whatever dufferences those make, simple maths says that a 50% chance on every attack does not mean 100% when you have two attacks each.