It may seem like a great idea to add more mythics into the normal egg pool for people to get. However, with the addition of Huskegon it’s now made limited mythics even harder to get. On average it takes 16 packs to hatch Y Ddraig Goch once. Adding just one mythic increased the average by a whole pack, 40 gems. If more get added into the pool then limited mythics will need an average of 20 packs or more!
What I recommend is these mythics only get added into the rare egg pool 24/7. For the normal egg pool there can be a max of 5 at any one time which rotate around the mythics that are not limited.
Alternatively, in festivals with a limited mythic, guarantee the first mythic hatched is a featured mythic.
Another idea is to make the boosted chance of the featured mythic increase each time you add more mythics into the egg pool, trying to keep as close as possible to the 2/3 chance it originally was.