They don't all require an enemy target to be used, but the ones that do, sure enough. I bring up Polyglot because it's directly comparable at 30s, but having the extra stack and the timer not freezing when max stacks are gained. Many Summoners have talked about the idea of Aetherflow being gained passively over time at 2 stacks/30s while in combat given that SE seem against the job ever getting the original Aetherflow back (which I would happily take over energy drain and siphon in a heartbeat).
The matter at hand is that SE went out of their way to make aspects of certain jobs more flexible with regards to downtime and with Summoner they went overboard in the other direction, for whatever the reason was. I for one am glad they've loosened that vice grip and admitted in previous discussions that they had gone about it wrong, in particular with how cooldowns would converge in a suboptimal manner. That is what lead to the cooldown adjustments with Trance.