When you are fed you can get what you want as soon as you have your IE done.
I personally wouldn't recommend getting Boots of Swiftness on Ashe as you can slow the enemy so he can't get away anyways. Berserker's Greaves are way better as they provide you the attackspeed you need for procing your Infinity Edge more often.
Furthermore, Madred is a more or less situational item as it doesn't provide real damage against squishy targets like the enemy's carries.
yeah but there not fun
If killin' folks in three hits ain't fun then dammit I don't wanna know what is.
Ahahhahaha, I can't even imagine how good you will be if you are gonna use a really efficient build for once xD
yeah but there not fun
Berserker's Greaves (or Mercury's Treads if necessary) are much better than Boots of Swiftness.
Madred's Bloodrazor really isn't a great option right now. I don't even consider it situational. You'd be better off building more AD.
Ionic Spark is terrible on AD carries. Phantom Dancer is a far superior source for attack speed.
Infinity Edge is great, though you'll probably want it a little earlier (assuming you purchased your build in the order shown).
End build:
Then a situational defense item. Usually Quicksilver Sash or Guardian Angel.
I personally wouldn't recommend getting Boots of Swiftness on Ashe as you can slow the enemy so he can't get away anyways. Berserker's Greaves are way better as they provide you the attackspeed you need for procing your Infinity Edge more often.
Furthermore, Madred is a more or less situational item as it doesn't provide real damage against squishy targets like the enemy's carries.