If your prefered method of leveling pets is exploring it can be difficult to do so as your pet count increases. To solve this problem I propose adding levels to the portal that increase the maximum number of located islands or the rate at which they refresh. One requirement for constructing each portal level would be a stable built to at least that level. The pet requirements could be things like any of the various genes that provide advantages when exploring or perhaps having explored a certain number of islands.

This idea has been flaoting around in my head for a while now, but seems even more relevant given the upcoming addition of various island types.

Adding more daily explores available to any group of players will require to reduce the loot  from every island for the sake of balance. Right now explore is the main source of new materials in the game. We can't alter nor the number of daily explores neither the size of islands because this will flood the market with unused materials. Reducing the amount of resources on islands and increasing the number of islands themselves will move us towards grind orientation. We tried this explore model in beta and declined it because it require players to spend a lot more time in game daily to use all of their daily possibilities.

I agree that there is a pretty good balance between the amount we can explore and the take-away. I really don't use up all my islands unless there is an event, or I really need something.

I have way too many pets to explore everyday. The grind would kill me. I could always get Energy Flow cards if I wanted more islands.