semantics, 0.9 pulses per second, continuously.
This isn't just semantics.
When talking about signals, "continuous" has a specific meaning.
This signal is off over 99% of the time. That means the battery can last almost 100 times as long, or it can use over 100 times (20dB) the signal power than a continuous signal. It also means that, if it is heard regularly for short bursts, the probability that it's a ULB rather than an artifact is much higher than the detection of a continuous signal - because this gives a signature unlikely to be found in nature or from unrelated technology.
In signal processing - i.e. what you need to do detection - all of this is very important.
In terms of search strategy, I suppose it could be thought of as "frequent" in the sense that you are likely to hear the signal more than once during a detection.