Launching from the same site along the same heading (azimuth) will result in orbits with the same inclination, but not necessarily the same ascending node. Say, for example, we launch due east from Cape Canaveral at 7:00 AM. We'd have an orbit with an inclination of 28.5 degrees (the latitude of Canaveral) with the orbit's ascending node 90 degrees west of Canaveral and the descending node 90 degrees east of Canaveral. Let's say we perform an identical launch three hours later at 10:00 AM. The resulting orbit will look the same as the first in relation to the launch site, but the launch site has moved. The Earth has rotated 45 degrees in the 3 hours since the 7:00 AM launch, thus the second orbit has ascending and descending nodes 45 degrees out of phase with the first orbit. The orbital planes are rotated 45 degrees to each other.

I'm sure you've noticed how the track of an orbiting spacecraft projected onto the Earth shifts to the west on each successive orbit. You can launch into the plane of that orbit only when the track passes over the launch site (that is, when the launch site rotates through the plane of the orbit). If the inclination of the orbit is less than the latitude of the launch site, the track will never touch the launch site, thus it is impossible to launch into that plane. If the inclination is greater than the launch site's latitude, the track will cross the launch site twice per day, thus there are two launch windows each day. If the inclination is equal to the launch site's latitude, then the track will just touch the launch site once per day, allowing only one launch window.

Edited to clarify explanation.

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