You should definitely feed data at the same time interval.
The only concept of time the HTM knows is the date encoding it’s getting. Other than that, it only knows that one point follows another. Your brain works similarly. It only knows that it gets a stream of input, that’s the only temporal structure inherent in the system. We add the idea of dates and times using encodings.
After a night’s sleep, you can’t tell what time it is until you get some contextual input from your environment (position of the sun, a watch). The HTM is the same way. The only way it knows about time is because we’re encoding time for it.
If you are not feeding in data at consistent time intervals (with consistent time interval date encodings in the input), it’s probably not going to make predictions the way you expect it to, because the prediction will also include a guess about what time interval encoding might be coming next. I’m not even sure if the classification step is going to work properly with staggered input timing.
(Hopefully I am right about this, please anyone correct me if I’m wrong.)