R : Assigning students to equal groups with random sampling. Understanding rep() argument length.out to sample()

I have 33 students I want to sort into groups of 6 (or as close as possible) on 5 different occasions. So I assign a number between 1 and 6 to the students on different occassions.

I've managed the following:

studentlist <- data.frame(seq(1:33))

studentlist$Occassion1 <- sample(factor(rep(1:6, length.out=nrow(studentlist)), 
                                 labels=paste0(1:6)))
studentlist$Occassion2 <- sample(factor(rep(1:6, length.out=nrow(studentlist)), 
                                 labels=paste0(1:6)))
studentlist$Occassion3 <- sample(factor(rep(1:6, length.out=nrow(studentlist)), 
                                 labels=paste0(1:6)))
studentlist$Occassion4 <- sample(factor(rep(1:6, length.out=nrow(studentlist)), 
                                 labels=paste0(1:6)))
studentlist$Occassion5 <- sample(factor(rep(1:6, length.out=nrow(studentlist)), 
                                 labels=paste0(1:6)))

This seems to work. As I've understood, I ask for each row a random sample between 1 and 6.

How does the length.out argument from rep() interact with sample()?

When I run a frequency table to check the sizes of the groups, I find the following:

numb=1,2,3,4,5,6. size=6,6,6,5,5,5.

I tried asking for 7 groups instead, and got group sizes of:

numb=1,2,3,4,5,6,7. size=5,5,5,5,5,4,4.

Why are they organised in this decreasing fashion?