Our DS had a rather poor Montessori preschool experience. On the positive side, the classroom was quiet and the teachers were in control (as opposed to his first preschool experience). On the negative side, it was too boring and independent for DS. The teacher told me she told him "I am not your mother and I can't spend all day with you." So if he didn't like the work, he'd sit at his table doing nothing. When he brought home blank pages he was supposed to have colored, he'd tell me "I can't color. I can only scribble. I only go outside the lines." When I relayed that to the teachers, they told me, Don't worry. Boys develop fine motor skills later than girls. Turns out he had a fine motor delay. The old chicken and the egg story. Did he have a fine motor delay because he never tried, or did he have fine motor delay because he had a fine motor delay? We'll never know.
Also, speaking of tedious - to develop a tripod grip, they would cut out maps of the US and the world using pushpins. They would simply poke the outlines again and again and again until the paper separated.
Montessori was not a good fit for our DS, but there were plenty of other children who thrived and became early advanced readers. Also, I regret that we sent him to preschool that had no toys. They said a child's work is play, which is nice in theory, but our guy needed more fun.
ps - I don't mean to be presumptuous by saying DS is PG, just sharing our experience fwiw!