Finding the right psychic or card reader for you is a whole thing. We get one reading from so many other folks, make sure they're not running a scam on us, and spend time building trust. It feels like when we find a good one, we should be fine.
Truth is, most folks need a second reader. Every reader brings bias into the readings, it's a side effect of what we do. We can see what the cards say, but part of what makes a reader good is the ability to draw from their own experience to tie the individual cards together. For example, I tend to think in terms that lead me to cushion or minimize sudden change. I don't miss it, but I'll make it smaller sometimes than it is. It's professional development for a reader to examine these biases and adjust for them. The trick here is to find two readers that compliment each other. Because I tend to be reserved, I pair well with a dramatic reader. The idea being that somewhere in the middle is likely where you need to be. Not to say that these biases will be enough to affect things on a regular basis, but once in a while it's important.
Where to apply a second reader
So, reading being so personal, I suggest finding someone you like and sticking with them for the most part. Where the second reading comes in, is that even a good reader has an off day, or a situation that they fail to grasp. If you normally resonate with, lets say me, but the reading you just got seems... off. That's when you'd want to call up your other reader, and set up something to read on the situation. Let them mostly read blind, so they don't walk in knowing what the other reader said, although once they've got going, feel free to ask about where it's different. Once they've got the basic outline, asking why someone else would've seen whatever can bring a LOT of clarity. Remember that as readers, all we have is one viewpoint on the energy in a situation. There's other viewpoints that help us, especially if the other reader uses a different tool. Different divination tools have different voices, almost like they speak different languages. That makes them better at saying different things, at least if the reader is good with the tool.
The traps we can fall into
There's a big danger here though, that we can fall into getting a second opinion reading just because we don't like what the first reader said. Sometimes a reading isn't what you want to hear. That's different than the reading not resonating or feeling off. If you have two good readers, all you'll do in those cases is throw money away to have the second reader say the same thing as the first. No reason to do that. On some level, you absolutely know if a reading feels off, or is just not what you want to hear.
Finding the RIGHT second reader
The thing to look for here is that each reader compliments each other. Often, your best bet is to go with folks that are very different from each other. It helps to have 2 different perspectives on things, even if they agree. I also suggest being transparent about them to each other, although both should be willing to look at your situation blind, to avoid confirmation bias. I'll also add for those of you that have spellwork done, that your readers on your spellwork shouldn't be your spellworker, as that's obviously a clear conflict of interest. Some folks have one regular reader, and rotate the second reader to try out many people. That increases the chance of getting someone no good, but also avoids the one reader being too close to your situation. If you feel confident judging the accuracy of new folks all the time, it's not a bad idea. Trust your instincts, and make sure you're comfortable with everyone who reads for you, considering how personal this kind of thing is.