The bands are further broken down into CW, data, SSB, AM, FM simplex, FM repeater and other segments to keep some order
The bands above 30 MHz are only broken down into SSB/AM/FM Simp/FM Rep by convention (band plans), not by regulation, with a couple of very minor exceptions. On 6 M and 2 M there are small designated CW only sections and 1.25 M has an odd digital forwarding allocation, but all other frequencies are open to all legal ham modes.
For example, on 2 meters 146.520 might be recognized and designated as the "FM Simplex Calling Frequency" but it is perfectly legal to transmit CW, AM, SSB, or data on that frequency, assuming you are in compliance in all other aspects except mode. This might make you a LID, but it is not illegal or in violation. And you could, for example, similarly use the "repeater output frequency" of 146.970 for any mode you want.
Indeed, in areas where there are no repeaters on a given frequency I see absolutely nothing wrong with using that frequency any way you want. Use it for simplex, use it for other modes, whatever. But it is up to you as an operator to know if you are or potentially might causing harmful interference to a coordinated repeater or even to another user in another mode who has the same thought as you. You must be in compliance with 97.101 in such operation.
Myself and a couple of locals regularly fire up in AM on 146.44, despite it being generally listed as in an FM Simplex area of the band. A couple of the guys have old tube type crystal operated 2 meter AM rigs and they had crystals for that frequency. Since APRS grabbed 144.390 and the rest of 144.300 to 144.500 went Oscar we like to stay away from the old AM calling freq of 144.400. So we end up using either an FM simplex or unused FM repeater output frequency for AM, we know it is legal and we know there are no repeaters we will cause any interference to. We try to avoid repeater input frequencies, even when there are no repeaters in reasonable distances on those frequencies. Even 2 meters sometimes can go rather long with a nice band opening and we would hate to accidentally get into someone’s repeater 800 miles away, regardless of how unlikely it is, and not realize it.
T!