To be fair, and without offence to anyone in general.
Writing a good episode takes time, brain power, and most importantly resources that are normally unobtainable in a short amount of time. Filler episodes are good in the sense they tend to buy the writers enough time to produce them. Not everyone may like them, but despite limited capacity they can still be enjoyed by a lot of people as its main goal is simply not to tune the audience out.
Furthermore, I assume that most people here are adults and not part of the target demographic. This show isn't made to be over-analyzed in the way that is, doesn't mean it can't be, but what I'm saying is that its supposed to be simple.
Personally, I don't think that the Iris episode was rushed. Originally, I thought it was going to be because I assumed that it was going to involve a lot more content. But no, the main premise was made clear from that start as a battle between Ash and Iris.