When is enough enough? 
Is 30% of your state enough tribute? 50%? 70% MORE?
Thankfully we don't have the spectacular vistas or tourist draws many other states have, but those we have are Federally controlled, as is access, for the most part to a lake with a shoreline longer than California's. Still, by virtue of mostly being private land, we had an oil boom in the Williston Basin when Obama's people were doing all they could to stop drilling. Other States have not been so fortunate.
(You don't even have to control all the land in the west, just the water and access to it.)
Any and all grants to become states are due to negotiations between the US govt( ie, existing states) and whoever wants to become a state.
There is not a standard, it is a negotiation.
There is little incentive or logic for existing states to permit a new state to joining without sufficient reasons to do so. The federal govt already owns the territories, so why give it up, especially as new state senators and congressmen would dilute the congressional influence of existing states?
Most new western states contributed a huge burden to the federal government to control the indigenous natives there, so necessitated military resources.
In spite of the US owning no lands within the state, that protection is the reason Texas gave up its extensive land holdings in the five later-formed states. It needed the federal government help to confront the Comanche and other tribes, as well as Mexican incursions. And Texas paid a lot for that protection, and federal govt greatly profited by obtaining extensive new lands.
Other states may have needed even more protection and were not nearly in the negotiating position that Texas was at the time.
Having said all that, I do admit that taking out federal control of lands makes it simpler for a state to secede as the federal lands would remain a sticking point on compensation. That point simply melts away one reason to block secession.
Another reason why I prefer a state to purchase from the feds the federal lands within a state.
And nothing prevents a state from purchasing federal lands, so why don't they if they really want them?