How many times can an alien use his power per encounter? Specifically aliens like Citidel and Reserve?

Jopustopin said:

This is not always clearly defined; sometimes you have to use context, a sense of good game design, and a little intuition to help you figure out the design intent. There is no specific rule that limits the number of times a power can be used per encounter, but sometimes there are clues that the designer only wanted it to work once per encounter.

Citadel:

• You have the power of Fortification. During each player’s turn, after destiny is drawn, you may play an attack card from your hand faceup next to any planet in any system as a citadel.
• If a planet with one or more citadels is targeted, after encounter cards are selected but before they are revealed, you may use this power to activate all citadels on the planet. If you do, add their combined value to the defense’s total for the encounter. If you activate your citadels on a planet and the defense loses the encounter, discard the citadels. Otherwise, they stay in place.

The first part is singular (play AN attack card ... as A citadel), so we have to interpret this as once per encounter; otherwise they would/should have said something like "one or more", "any number of", etc.

The second part is all-or-nothing: activate all citadels on that planet or none.

Reserve:

• You have the power to Reinforce. As a main player or ally, after encounter cards are revealed, you may use this power to play one or more attack cards of 06 or less from your hand as if they were reinforcement cards of their listed value.
• As a main player or ally, when another player plays a reinforcement card, you may use this power and discard a negotiate card to cancel and discard that reinforcement card.

The first part clearly says "one or more". The second part appears to be usable each time it comes up (i.e., more than once per encounter). If they had wanted the second part to be only once per encounter, they would/should have said something like "You may use this power to cancel and discard one reinforcement card per encounter by discarding a negotiate card from your hand". So there's no apparent attempt to limit it, and it's inherently balanced by the fact that you can only have so many negotiate cards in your hand, so this seems multiple-use to me.

Resolving unclear situations can be tricky; sometimes you have to ask yourself two questions: (1) if they meant interpretation #1 would they really have written it like this? If they meant interpretation #2 would they really have written it like this? And then see which of those two questions you can answer with a more convincing "yes".