Quite simple to answer. Max improvement in percentage lays between 20 and 40%. That’s why flare gave us an average of 30% max improvement. After a dozen forges the improvement start to decrease rapidly till it’s useless to forge. Who will forge when improvement becomes 0.01% or even less per forge??? That’s useless, so there is a limit.
You increased speed of knights by 33.78%. I expect for every extra forge the improvement will decrease rapidly and if not yet, it soon will decrease. 40% means possible speed of 3.15.
Let’s calculate it with numbers. Standard range of archers is 3.5. When we take even the most extreme number of 40% imrovement, you can only get the range up to 4.9. More realistic is somewhere between 30% and 40% so possible range is between 4.55 and 4.9. With this in mind, you will never be able to hit a tower on opposite lane with archers. It’s more likely that one of your archers comes in range of one of those those towers (walking close to the edge), activates the tower and as result heavy damage to your archers. Of course the hero can bounce back incoming (skull) bombs, but it will be a different story when multiple towers start to fire simultaniously. You need the spells to protect your archers till they are in range and that’s not always possible.
Other ranged troops have a range of at least 5(pyro) while most even start at range 5.5. Guess who is going to be hit first? Also here you need your spells to prevent damage. Nice that your archers have a theoretical range of 4.9, a defending (storm) cannon has range 6 and a bunch of them will target your army of archers way out of their max range. The storm cannons stay on that same spot, take out an archer, target another archer and will keep shooting untill they have no target any longer (meaning byebye archers).
An arblaster however with 30% range improvement can get a range of 7.15 (I guess it won’t be 40% otherwhise it even could be 7.7!). Speed of archer is 1.73. Total difference in range in extreme advantage situation of archer is 7.15-4.9 = 2.25 range difference. We know that speed of archer is 1.73 so he needs 1.3 seconds before he even is in range to fire at an arblaster. He already got hit at least with 5 arrows per arblaster, so he is dead before even able to shoot, when we increase both ranges to max. And spells won’t help you there, when arbs are shooting from 7.15 distance, your spells won’t be able to hit them, unless you need to run forward to close the gap (risking your hero to become a target and shot down)
Even in comparison with other troops that aren’t increased the archers will be last troop that is able to fire. They will get hit first, before able to deal a blow. And before you are able to deal damage with a troop, you must make sure it’s still alive plus in range. Not all bases have only non ranged troops, be aware of that.
When you still need to decide where you should spend your pearls on, I would not go for range of troops with lowest range.