I havent used a tillering stick or tree on my last 4 bows. Here's how i've been doing it.
I am getting a better eye for floor tillering. I floor tiller and look where areas are stiff and then rasp those areas to get them bending. I slowly work the handle down as well since i typically make bows that bend in the handle. After floor tiller, i will bend the bow against my knee to see if one limb is noticibly stronger than another and will take wood off the stronger one in long sweeps. Then i brace the bow at a very low brace height, say 3 inches. I bring the handle close to my face with my left army and push away from my face with my right hand and sight down the limb to see the bend.I do this for both limbs. I pull on the bow to feel and see what weight feels right(i like doing this as opposed to the tree because you can really feel how the wood is responding to being pulled). I am constantly pulling the bow to work it while tillering. When i reach about 25 or 26 inches of draw, i go to the handle and begin taking wood off of there till i feel it bend at 28 inches.
This is how i have been doing it. I enjoy making bows more this way than standing back and pulling on a rope. The tiller may not be as perfect but out of 4 bows only 1 has broken so far and thats because i pulled it too far too early. Of course its still a learning process.