Practical Control Loops

It is not totally clear what you are seeking answers to but maybe this will help.

In real time the transient time is totally dependent on how the system is configured and tuned in relation to the process system dynamics.

Some critical things to consider are:

Is the minimum and/or maximum SP or PV value(s) required to be clamped?

Smaller differences between Min & max SP values yield shorter transient times and vice versa.

What are the PID values?

Proportional/Gain values directly affect the loop reaction time. Lower proportional or higher gain values cause the ramp rate to become more steep with shorter transient time and vice-versa.

The Integral and Deriative values directly affect "overshoot" and recovery time which directly affect transient time when the loop is seeking stability after a SP change.

Simulated loops require the user to manipulate these values then observe the loop reaction and select the best case, values for accurately controlling the process.

There's always some transient behavior at start up. Some time always elapses before input becomes output and is fed back to input again. If the loop is stable (and damped), these transients soon die out to imperceptible amplitude and you have your steady state.

I agree that your question is not very clear. With it not being clear, you will likely attract many silly answers. Remember most silly answers are attempts to enlighten with a smile.

I think the answer to your question will be best answered with an examination of one of the simplest control loop systems. I will choose a system used for millennia before control theory existed, the fluid tank with a float controlled fill valve. A simulator will use the collection of exponential differential equations that control theory provides to explain how this simple feedback control system functions. As you should remember from your differential equation class, an exponential equation asymptotically approaches a steady state value. It never actually reaches it. Thus control theory implies that a float valve should never actually fully stop fluid from flowing into the tank but only gradually reduce the flow to a smaller and smaller rate. Yet in real life the flow through this valve matches the theoretical equations until it completely closes.

Simulated is one you run in the computer, real is actual stuff, like how real is your question?

Your question is poorly worded, the best I can give is a general answer.

Control loops are designed to provide a steady control to a process or positioning. If the 'Control' input does not change, then the only changes the loop will be making will be corrective actions to reduce the 'Feedback/Error' input to zero(1). If the Feedback/Error is zero, then there are no changes needed and the loop output will be steady-state.

Notes:

1) 'zero' defined as 'whatever signal indicates that the process/position is matching the setpoint. It may not be a 0V signal, but it's traditional to call a calibrated reference a 'zero' to allude to the zero on a number line or the origin point (the zero-zero point) on a Cartesian plane.

If the control loop is properly designed. An improperly designed loop can make a real mess of things including complete destruction.

Well, of COURSE I'm talking about a 'properly designed' control loop. The way to explain theories is using a 'perfect' model as a reference, to show how things SHOULD work if the world followed the maths precisely. Then after the theory is understood, you move on to the 'practice' portion of 'theory and practice,' talking about how things never reach that mathematically perfect state, that Op-Amps/Diferential Amps have two pins that you should connect a variable resistor across, to be able to 'fine tune' the switchover point to be as close to zero as you can get it (since all Op/Dif amps have an internal bias one way or the other away from the perfect point of 'switchover is when Vin+ = Vin-, and the bias varies from chip to chip even in the same manufacturing batch).