One of our children took a number of classes through DE and it saved about a years worth of tuition so definitely worth it in that case. That said he still had to take extra math at the college level to make up for the math shortages but some of those classes for General Ed requirements.
For my current senior I paid for the college credit for his pre-Calc class last year, however it was through our flagship. I did my homework first and based on his school list at the time it counted at enough of his schools as either a general Ed requirement, the waiver of a block or as a placement test to make sense. If he goes to his financial safety it was worth the price, if he ends up elsewhere it remains to be seen as the list of schools has changed since then.
I am not paying for it for my current sophomore in the same class. He’s a track ahead of his brother and it is of much less benefit to him than the 2 AP calc tests will be and the combined price of those 2 is less than the 5 credits from the flagship,