Technically yes, but in practice, it depends. My half-moon design is based off those sold by Apogee, but I would imagine that
eventually, all baffles will wear out and need to be replaced. The only question is will another critical component of the rocket wear out first or will the rocket otherwise be lost before the baffle's life ends?
Like Back_at_it mentioned, how long a baffle lasts will depend on what you use to create it. But there are other factors to consider, such as the baffle's physical design and its proximity to the ejection charge.
A baffle will last longer if it's made from more durable materials (from a fire-resistance perspective). But where you place the baffle and how freely gases and hot bits can flow through the baffle will also affect its life.
My experience with baffles is only in BT-20 and BT-50 sized rockets. But from my observations, it seems like wear and tear due to heat exposure (hot gasses and burning bits) have a bigger impact on baffle life than physical forces on the baffle (like built-up pressure). And because you only want to reinforce your baffle so much, I think your "weight budget" is better spent on coating the inside of the baffle with epoxy or glue to make it more heat resistant than using a stiffer baffle material.
For example, in my
BT-20 removale baffle design, the half-moon pieces are made out of 1/16" balsa, paper, and JB Weld. Yet after 8 test launches, they show no signs of fatigue or failure. Yet the coupler's housing (the yellow engine spacer) is showing signs of not lasting that much longer. However, the burn marks on the yellow engine spacer are only showing up in parts of the baffle that were NOT coated with glue or epoxy to provide heat/fire protection. I'm doing more tests to learn more about how to make baffles last longer, as well as test them in more extreme conditions, ie next to a C engine instead of an A engine.
In summary: the
further away your baffle is from the ejection charge, the
more room your baffle has inside to allow the flow of hot gases and burning bits, the
more fire resistant materials and building techniques you use, the longer you baffle will last. But if you push these variables so far, your baffle will become excessively heavy and likely overkill for your application. It may also be of a certain size or in a certain location that doesn't work well for your rocket's design and performance expectations.
Here's my take: if you can build your baffle to be removable, do it. Even if your baffle is built so robustly, it'll last thousands of launches, it's still nice to be able to remove your baffle to clear up any potential blockages or crud that builds up. Some build up is nice that it can help insulate your baffle from the heat. But too much means inhibited gas flow and extra weight carried by your rocket. Another benefit is that if you can tie your shock cord to the baffle, a removable baffle is a great way to replace and/or inspect your shock cord.
A removable baffle also provides flexibility to use any type of baffle. For instance, right now, I'm thinking about having 2 types of baffles: a performance baffle and an endurance baffle. The former will be as light as possible and likely only last 3-6 launches. But the endurance baffle will be built more robustly and should last more than 20 launches (or for all practical purposes, last forever). But it may be anywhere from 50% to 75% heavier.