I don't have any first hand experience, but I do understand and agree with why a project should be tracked this way. Your planned value will create a target to aim for by a certain date, the earned value will put a dollar amount on what work has been completed and when you take them both into account you will be able to see monetarily how ahead or behind schedule the project is. Now the more important indicator, in my opinion, is the cost variance because you may be on schedule when comparing the earned value to the planned value, but when you check the earned value against the actual value you may be over budget. So it is important to consult both SV and CV during the project, I wouldn't take one metric without the other.

Both variance types are crucial when trying to stay within the scope of the project. Schedule variance is calculated by subtracting the planned value out from the earned value (EV-PV). Schedule variance gives the PM an idea of where they are at in the project; which is necessary because it will allow them to know whether the project needs to be sped up or remain at its current progress. Cost variance is found by subtracting the actual cost from the earned value (EV-AC). As previously mentioned, cost variance tells where the project is at in terms of budget consumption. I would not compare these two and say one is more important than the other because both are equally required. A PM most certainly needs to know how much is left in the budget, but they also need to know how much longer the project will take to complete in order to properly plan how much more of the budget can be consumed, or if they need to acquire more money. Both are interdependent in a way, and allow for a much broader view of what's to come in terms of project requirements. The way I see you really shouldn't have one without the other.

It seems that the difference between planned value (PV) and earned value (EV) is a project's way to determine whether or not it is on track on a financial level. If a project is budgeted at $5 million with a 5 year duration, then its PV and EV fall under the same date and time in order to compare the two variables. At 2 years, the PV will therefore be $2 million, and if the EV is below that amount, then the project is simply behind schedule. On the contrary, if the EV is above $2 million, then it will tell upper management that their project is ahead of schedule and perhaps improvements can be implemented with the surplus budget. Another variable that is used in project management that sets PV and EV as a ratio is the schedule performance index (SPI) in that SPI = EV/PV (1). Similar to scheduled variance, a SPI value greater than 1 is an indication that more work is being done than initially planned while a SPI below 1 states that the work being done is not meeting expectations. SPI is really just an indicator for the current work rate at any given time, but does not determine if the project is ahead of schedule or not.

One main question that goes more in depth with a project's values and variances is how are these values (EV, PV, etc) determined or measured? How is the monetary value of a project measured at any given point in time in terms of budget and percent completed? What if a company has a project that is halfway complete, but decides that it no longer wants to carry the project even though it has an EV of $1 million. Is it possible for the company to sell what they have to another company for its EV value? If so, is it likely for there to be conflict between companies in determining a project's EV?

Reference
(1) Project Management Institute website

The monitoring and control process of the project management consists of the activities involved to observe the process after project implementation, identify problems and risk, and deploy a mitigation strategy to control the new process. Monitoring and Controlling project work involves tracking the actual project performance with the planned project management activities. 

Project cost performance is measured by comparing EV to AC. Where the difference shows whether the project was spent more than planned or less or is according to plan.

Whereas, schedule performance is determined by comparing EV to PV. By comparing the two, we can determine whether work has been done than what should have been done, and whether the project is proceeding according to the timeline, is ahead or behind. We make these comparisons by calculating differences and performance indicators

SV = EV – PV

If the result is positive (greater than zero), this indicates that the value of the activities carried out is greater than the value of the activities that were planned to be carried out at that moment and that means that you are ahead of the approved timeframe (Ahead of Schedule). But if the result is negative (less than zero), this means that you have implemented activities that are less than the value of the activities that you were supposed to implement according to the approved plan. And then you are behind the behind schedule. also, that the result is equal to (zero), this means that you are going according to the time plan completely

CV = EV – AC

The result is positive (greater than zero), this indicates that the actual spending rate is less than the value of the activities carried out and that you are still under the limits of the under budget. But if the result is negative (less than zero), this means that you actually spent more money to implement those activities than the value of those activities or in other words, greater than the material return from those activities or the value gained for them. And then you have crossed the limits of Over Budget.  also, that the result is equal to (zero), this means that you are going according to the budget completely