There are ready made stair treads, however the species is rarely a perfect match, and often they are made of veneer plywood or laminate, which doesn't last particularly well when given the daily beating that stair treads take.
When people are spending money on real hardwood--or wide plank hardwood, they deserve to have the stairs done properly as well.
For this job I chose wood directly from a wide plank flooring mill near Barrie Ontario . Merv Gardener dries his lumber to 6% for flooring--so I know that these treads will be stable.
When it comes to biscuits we used a Beech Biscuit, with an exterior epoxy glue which when mixed with sawdust from the sander, I can tint to the same oak color.
Of course when I went to do this I realized I lent a number of my clamps to one of our builders, and haven't seen them return yet! So, I glued them up in a number of small batches. This job was about 15 treads including the stairs down to the basement.
When it comes to putting the flooring down, we use PL Premium adhesive and a few well hidden finish nails, or countersunk and plugged screws.
Really, with a good bed of screws you will find that treads are not removable... without destroying the sub tread.
We always make an extra tread just in case something goes wrong. This time we had the lowest tread break as we spun the newel into place--just a bad grain. I ended up having to score the tread in about 10 places and using a chisel to be able to remove it from the sub tread.