Some problems should be given without solutions, because it will help a student identify when their use of solutions is becoming a crutch to help them solve pro

Some problems should be given without solutions, because it will help a student identify when their use of solutions is becoming a crutch to help them solve problems. But as you point out, some problems need to come with solutions so a student can check their work. I assume this is a reason why so many textbooks have answers for every other question instead of answers for no questions or all questions. With technology we can improve this by having an answer that is available only after the problem has been attempted, but the online answer checkers seem to introduce a host of other problems that make it unclear if there is any net advantage.