how long do you guys make the leaders?
For Sink Tips it'll usually be anywhere from 2 to 6 feet depending on the circumstances- typically sink tip applications are on a river to get your fly down so putting a long leader on them may be counter productive, hence the shorter leader, and it doesn't have to be tapered either- the entire leader can be one section of a certain pound test monofilament.. For Sinking lines, you can go as short as 2-3 feet and as along as 20 feet depending on water/application. Sinking lines are typically lake applications, and 2-3 feet may be in a murkier lake, you could go as much as 20 feet if you were trolling in a super clear lake with wary fish. Again, you generally don't need a tapered leader as any sinking application you are not worried about presentation as much as you're fishing below the surface so you just want your fly to turn over, that's it.
With floating lines, you may fish a weighted fly or a non weighted fly, of which the non weighted fly may or may not sink (if you're fishing a subsurface pattern or a dry fly). A good general rule is a floating line leader should be about as long as your rod or longer. Most Spey guys will fish leaders as long as their rod up to as much as 20 feet long on a floating line. A tapered leader here, especially with delicate presentations, works, whether built or not built (bought). Some spey guys won't even make or buy a tapered leader - they'll just run straight mono from 12-20 feet. The reason is because the spey lines carry so much energy that they have no problem turning over flies with straight mono - the thicker butt section of the leader doesn't do as much, plus you have less knots. This is often fine when you're fishing 12 pound leader, but when you're in a trout application with a 3 or 4 weight line and a delicate dry fly a 3 pound tippet isn't gonna fly in this application and a tapered leader becomes more neccessary so you have some of the fly lines energy imparted down your leader towards turning over your fly, plus it does a nicer job of turning over your fly delicately.