The main problem with long tufts is keeping them in place (standing up) while they dry... With a bit of paper you can do the following structure.
1 - Perforated paper with some folds so that the holes are away from the ground.
2 - Non adherent paper, this is where the glue goes
3 - Paper frame duck-taped to a movable surface since you want your little tuft factory mobile
I choose a big distance from the ground because I need big and medium tall tufts.
I created two assembly lines so that I can clear more units per day.
I use cheap PVA glue and some tall grass from any company really.
Lay down some glue blobs on the non adherent paper.
Grab the tall grass and make sure both extremities are secure. If you don't you will have loads of grass bits flying around everywhere.
Insert tuft trough the hole and let it stick to the glue beneath it.
Make sure you do different lengths and volumes so that you can have more options when flocking your terrain.
Once PVA is dried you lift the punched paper to reveal the results.
Thats it tuft done!
If some of them have to much glue on the base you make sure you cut off the extra.
Lots of different sizes and shapes.
I keep them in a bag and the leftovers I also keep them in a bag so I can use them later on as scatter flock.
You can do plenty of tufts very fast this way.