My approach is: landscapes are generally 'static' subjects, so we don't need a fast (short) shutter speed. So I'll often shoot in aperture priority mode and set that to reflect the depth of field I want in focus, which for most landscapes is maximum. So I set a small aperture, say f11-f16. I set ISO to 100 to get the best quality image (ie. least sensor noise - my cameras an aging Canon 300D!).

If you're serious about getting a good image you'll have brought along your tripod, so it shouldn't be a problem if the shutter speed then ends up being longer than you might get away with handheld.

If you haven't a support handy, you'll have to compromise on something - either ISO (increase to 200 or 400) or set a larger aperture so the shutter speed reduces. Or do both - doesn't cost anything!

The great thing about digital photography is its dead easy to experiment - like you did here. So try this, then put the camera in its landscape mode and see what it changes.