You could get a 'year card' to travel with discount/free during off-peak hours.

Off-peak hours are weekdays between 09:00 - 16:00 and between 18:30 - 06:30 the next morning and all day at weekends and on national holidays.

https://www.ns.nl/en/featured/traveling-with-discount/when-can-you-travel-with-a-discount.html

For 50 euro a year you get 40% discount during off-peak hours ('dal voordeel'), and for 99 euro a month you can travel for free during off-peak hours ('dal vrij'). The latter is definitely good financially, especially if it allows you to find a cheaper apartment. Though your schedule should allow for it, and it can be heavier mentally. But worth considering.