I don't know, at times it felt more like they were intentionally trying to make the teasers shorter and more meaningless. Or even more frustrating, when we see the Xindi attack, this is meant to be one of the show's defining moments that arguably sets the tone for much of the remainder of the series, and all it is is a forty second CG sequence. Or throughout the third season, Impulse's teaser is literally just twenty or thirty seconds of T'Pol screaming as she's strapped to the biobed. Or Zero Hour, where the Xindi-Reptiles talk their evil plans while eating mice.
I remember when the third season aired, me and my sister had a thing going on, she was watching a show that was on at the same time as Enterprise, and I would show up after Enterprise's teaser and credits were done to inform her of such, and almost always her show hadn't even begun its credits yet.