Molniya orbits[0] can provide continuous coverage of the poles if you've got a couple in orbit. The orbit has an extremely high altitude apogee and low altitude perigee. The high altitude apogee gives it a long dwell time (from the perspective of the ground).

It wouldn't be the most practical orbit for narrow FOV imagery but for polar weather, communications, and monitoring for things like over the pole missile launches they're pretty useful.

[0] https://en.m.wikipedia.org/wiki/Molniya_orbit