How exactly do terminals work?

I plan on taking an all domestic, all delta flight. I was curious if airlines had organized terminals like say one for my delta domestic, one for delta international, SW domestic, so on and so on. I wish to know if this means i could keep layovers shorter considering I'd be dropped off in the same spot that I'd leave from

Nope

The length of layovers has nothing to do with where an airline's gates are within an airport terminal and everything to do with when the airline you're using has a connecting flight departing from that airport to your next destination.

Most airports are small and only have one terminal. Usually each airline's gates are grouped together.

On the other hand, some larger airports have multiple terminals that aren't connected, or not very well, like LAX and JFK. In some cases, an airline with a large presence there might have flights at multiple terminals. Generally, though, each airline will either have its own terminal/concourse or operate most of its flights out of a section of a terminal/concourse.

There are about 5,000 Airports in the USA for commercial flights.
Some are very large and some are very small.
The Large Airports can be one large building with about 20-40 parking places/gates for planes.
The very large Airports Separate things into different buildings/Terminals with 100 or more parking places/gates for flights
With two one is Usually for the International Arrivals.
The major Airline serving that Airport may have enough flights to justify their own terminal
You enter at one end and exit at the other.

Usually with the arrivals direction and departure direction of passenger on separate floors.

Short lay overs are possible. You flights could be side by side and a change could take less than 20 minutes.

Trying to push the limits can backfire on you. Your flights might be up to mile apart walking distance.

your first flight could have some issue and depart a few minutes late, YOU DO NOT get next flight out if you miss yours.
You get next available seat could be an hour or a day later.

It is reasonable to allow at least an hour and for a larger airport 2-3 hours. There's no need to aim for getting to next flight as they close to door just as you get on or just before you get there.

Sometimes it all works out. Sometimes it just does not.

Only you know what it is worth in your time to miss the connection.

Do you know the weather forecast for a few hours around your flight path your day of travel?
A big storm a thousand miles away could disrupt the schedule of the planes used for your flights.

With thousands of others also needing new flights you might wait for a day or two for a seat. You do not an all expense FREE stay for a few days while you wait.

Allow for REASONABLE amount of time for each of your stops. And change of plane only you know the cost to you of missing a connection.

Airlines will if you are waiting for a later flight usually allow you at no charge if seats are available to take an earlier departure the day you are travelling. Your first check in place could check for you and alter the rest of your flights to earlier ones. On a day with weather issues or your first flight being delayed your stress will appreciate having few hours extra just in case.

the break between flights can seem long. A meal, a beverage a toilet stop can easily take up 30-45 minutes of your waiting time a far gate can be a 30 minute walk.

Are you a marathon runner or just a regular speed walker?

Exactly how you would imagine. The larger the airport the more terminals they would have, they have flights split by operators, international or domestic departures, etc. It really depends on if your flying to LAX or Little Rock