Deer can be broken down as mule/whitetail. Whitetail is highly on private land only with the exception of some places in eastern CO that have public access. Mule deer are much more like elk in the mountains with lots of public access.

Just like elk there are various archery, muzzleloader, and rifle seasons.
Depending on the units and what the populations are the number of tags can vary greatly.

The basic premise is they want a certain number of tags per unit given past successful statistics. This keeps the population in check and the numbers where they want them.
The hard part is units that are almost all private land, that is where you will see long seasons, season choice tags, B/C licenses. The unit may have a lot of animals but due to limited access the common guy won’t put in the effort or won’t be able to get access to private ground. For this same reason you will see guides buying landowners tags and offering them to clients as they have low pressure, easy access and most likely great success rates.

Coming up on 12/1-12/15 is the late rifle deer season. I don’t feel like digging into the regs book, but I think it is mostly if not only on the eastern plains.

As for your question on guided/landowner tags, it varies but mostly mirrors current seasons for public land. Even the guides are getting tags which they buy from landowners or have their clients apply for.

Another example is my friend who lives in the foothills west of ft. Collins. He can get a cow elk tag that lasts several months. Just needs a cow to cruise by on his property when he is home and he is set. Deer on the other hand is specific to the different seasons and he typically has best success in the late rifle season during the rut.

Hope that solves a little bit in this highly complicated process.