SL, you will find out during your flying career that is is quite common for a VOR to be unavailable, be it by NOTAM for maintenance or you are in an area where radial x to y is unreliably received or it is just plain broken. A pilot unfamiliar with an area will never rely on a sole VOR, so no surprise or harm. Even if a VOR is decommissioned, it may be temporary, you can't really tell for sure and many of them are also stored in serviceable condition for emergencies with a few hours recovery for the unlikely event of GPS outage. the next solar storm will come and they usually keep the reliable stuff handy for backup. He who navigates on VOR is typically also able to do the dead reckoning as backup ;-).