That is ASSUMING everything goes smoothly, as it rarely does.
EOL's are at the mercy of the BB's and that is based on O/B freight that needs to be serviced (sometimes).
O/B direct rail freight is left to sit regularly. I/B rail freight is regularly not dispatched until last minute, just to barely meet T/C times. This leaves drivers waiting for freight and late peddle starts that already have longer stem times. It seems simple, but the cogs are worn and the machine needs a major tune up.
Back to topic, absenteeism is the result of overworked employees that are exhausted, disgusted and/or out of hours.
Some guys are okay with 55-60 hrs weekly. Some guys do 50 hrs work in 40 so as to get out the gate to have a life. Some guys get nothing done, regardless of how long they are punched in, but that group is a significant minority. There can only be one or two people in the whole system that have 2 weeks or less vacation....
In a 30 person barn with 1/2 the board w/3 weeks and the rest w/4 weeks, that's 2 workers vacationing every full week. Add in sick days, p/h's, b-days and anniversaries, the 10% board is exhausted before anything else is covered.
Change the thread name to "understaffing/ we need more help!!!"
Now, reality for your numbers.
We get 350-400 bills on a Monday. We have 32 working, no casuals. (two on hard layoff plus two out on comp.) (That makes 28 total) We deliver 300 plus and pick up 100 - 120. The rest of the week tapers down to 180 - 200 I/B on Friday and 150 or more O/B.
We cover 1600 square miles.
We have an I/B crew of 5 and an O/B crew of 3. Your numbers are from a fantasy world.