My honest opinion would be no. But realistically, yes. Why? Allow me to explain.
I would prefer there not to be entire episodes dedicated to side characters. This is because I find those to be fillers. While side characters may have a very distinctive personality, you do not feel attached to them. Attachment is gained by showing up more often, playing an important role in episodes, having things to offer to the story and the cast and by building relationships with established lead characters. Side characters are designed to play a supporting role in the stories of the Mane 6. It’s hard enough as it is to make an interesting episode dedicated to only one of the Mane 6. I can’t imagine being interested in watching 22 minutes of a character that had nothing of importance to offer, has no properly established relationships with the Mane 6 and have only been shown once or twice before.
More specifically, Daring Do. Why not an episode dedicated to Daring Do? Firstly, because even in Friendship is Magic, Daring Do is a fictional character, a full-length episode about a fictional fictional character just screams lack of creativity. Secondly, I’ve had enough of her as it is. She basically already had her own episode: Read it and Weep. With Rainbow Dash reading the book half of the episode, she had sufficient screen time. Not only did the cliche Daring Do stories have a boring plot, Read it and Weep, because half of the episode was Rainbow Dash overly obsessing over a book, made for a terrible Friendship is Magic episode plot.
But why realistically yes? Because if we want many seasons, with many episodes each, we have to accept and embrace filler episodes. It takes a lot of effort to write a good story that balances the involvement of every character in the show. You can’t expect 26 episodes per season to have a full story with a lesson at the end. None of the other seasons have and none of them will. It’s only a matter of time before we get bored of Mane 6 and Cutiemark Crusader filler episodes. On a certain point, the writers will have to branch out to side characters that have already been introduced, including Daring Do. Might as well be in season 4 and be done with it.
I hope I haven’t upset you, @LoyalSpectrum, or anyone for that matter. But apart from my personal dislike towards Daring Do, I just don’t feel attached enough to her to enjoy a full episode about her.