A decade ago I read this same advice in "The Curmudgeon's Guide to Practicing Law": spend at least a little time trying to solve the problem before you look to how other's have solved it. One benefit is that occasionally you may stumble on a better method. But the more common benefits is that it helps develop your problem-solving skills and it primes you to understand and appreciate existing solutions.

What if you’ve already read the prior work before trying to solve the problem?

> If you read the prior work too early to you get locked into existing mindsets.

I agree, though in some cases coming up with your own ideas first can result in you becoming attached to them, because they are your own. It is unlikely for this to happen if you read the prior work first.

Though I think overall reading the prior work later is probably still a good idea, but with the intention not to become too impressed with whatever you come up before.