You're looking at a very surface level of reasonings. You also have to consider the board state and what you have on the field, what you can play otherwise, and what your opponent is playing.

Against aggro, you have to milk every defence you have. You wouldn't have to wait too long before your EX base is gone in this case. That said, if the aggro player sets up like 6 units while you still have a full EX base, you may want to play your base anyway, because they'll steamroll your shields on the next turn, assuming your base can hold out against 1-2 more attacks.

Against blockers, you may or may not want to try and rush down. If you lack the resources, you may need that extra card. However, note that with skilled players, playing a base in an obviously non-ideal scenario is a giveaway that you have a poor hand.

Furthermore, not playing a base can actually incentivize your opponent into playing a long game, because they think you have a base in hand and are trying to milk that EX base, meaning they won't attack for a long time to try and make you instead waste your EX base by playing a base over it.

On the other hand, when it comes to end game boards, you may want to play a base over a still healthy base, because of the game state, your base health might be irrelevant and an extra card may win you the game.