While I'm not a big fan of Wikipedia, I usually find that for advanced electronics and communications topics, its a decent resource for just ballparking specs and getting an understanding.

https://en.wikipedia.org/wiki/LTE_(telecommunication)

Its been almost 10 years since I finished my degree program in this general area, but I still get the basics. From what I've read on different sites, 4G LTE can run anywhere from 50 to 300Mbps. And while towers can have bandwidths from 1.4Ghz to 20Ghz, if the tower/carrier is using a form of CDMA (code division multiple access), you should have a 5Ghz bw and 200 user capacity.

Smaller than what I expected in terms of users and data capacity per tower. You may be using a significant chunk of the capacity in the evenings. But every cell tower is custom to the needs of the area. Urban areas will have more towers covering smaller areas to accomodate the larger population density. I would assume that since you are in the Detroit area, there are many different towers that you may be able to ping to/from as the data load changes. This may be the cause of some of your lag like issues sometimes, because the network may move you around to keep you connected while also providing you and the other customers continued access.

This fits. We have 3 towers I can connect to. One visible from my house, one a mile down the road by my parents, and one near to ProbablyLast. I am infrequently switched to EV-DO rev A on the close tower, and sometimes switched to the tower by my parents' house, though only on LTE. The low number of users is a bit weird though. We've got around 2000 people per square mile of land in this area, and each cell around here appears to have a half mile to mile radius from what I remember looking at a map. Even if Sprint is only serving 10% of local customers, there's almost no safety factor there.

What does the 5GHz bandwidth mean? And I assume it does do CDMA as well.

Your carrier Sprint has purchased a band of frequencies it can transmit at from the FCC. I see that Sprint uses LTE on 3 bands; 2.5Ghz, 1900Mhz, and 800Mhz. If we use 1900 as an example, it has a total bandwidth of 60Mhz. Inside that band it can and does split into smaller channels at different sizes. 1.4, 3, 5, 10, 15, and 20Mhz are all available in your 1900 LTE band. So at 5Mhz you could have 12 channels from a 60Mhz bw. 12 x 200 would give you a total of 2400 customers for that cell tower assuming its only using that frequency. It may be able to give you access to the other two (2.5Ghz and 800Mhz) bands as well. Obviously you can get more customers with a smaller channel bw, say 1.4Mhz, but data throughput is also reduced because bw is one of the main determining factors for data transmission. (search Nyquist rate if you are interested in learning more)

I'd assume that you'll see better performance at night because the system has the capability to auto adjust channel bandwidth based on its actual demand. So you may get the 20Mhz channel vs the 5Hhz channel size. It's just a likely that the frequencies are preset by the engineers based on the projected customer requirements, so you are stuck with 5Mhz. In that case to service more customers they would need more towers spaced closer together. Now that I think about it, this is most likely how its being done.