It's been at least 6 months that I'm experiencing lots of deja vu-like events.
By a lot I mean at least one per week. It's been increasing gradually.
I would like to ask if it's been reported frequently in the context of some stage of insight. 
I'm wondering if it can be related to practice or if it can be a symptom of other things.
For example I notice a thougt and upon noticing, a strong sense of "this moment already happened" arises. Then I see a blue pencil and the seeing of the blue pencil comes with the same feeling of "this moment already happened". And it gets more intense as more events chain together forming a complex chain of events that also comes with the same feeling "this chain of events already happened in the same order", which is unlikely to the point it's not even realistic.
I could understand getting a deja vu on a road I drive every day, but this is another level.
I hope I explained myself clearly.

Are you practicing mindfulness  in daily life? Drive to work ? Brushing your teeth etc? How long have you been doing this?  Just need some info if you have any sort of practice. 

Yeah, how has practice been lately? 

​​​​​​​How do you feel before and after the deja vus?

    Hey Walking Rain,

A quick Pubmed search yields that frequent déjà-vus can be related with several conditions, including high anxiety, but there is also a well-documented connection with seizures and temporal lobe epilepsy, as well as a less well documented connection with cardiovascular disease. Some papers observe that seizure-related déjà-vus can be qualitatively different from normal déjà-vus.

Have you been experiencing high-anxiety? Do you have any known medical condition, e.g. a psychiatric diagnosis, epilepsy, seizures, cardiovascular disease ?

The phenomena you describe, with this compounding effect, duration, and frequency of occurrence, do not sound like the types of déjà-vus I've had. I suppose it could just be an emergent phenomenon related with your practice, or a random thing, but since it's been happening for 6 months I would advise consulting with your physician, who will perhaps recommend a consult with a neurologist if needed. 

Not wanting to  sound worrying, but ​​​​​​this is likely not the kind of stuff people with only their own personal meditation practice/reading plus perhaps some teaching experience but without any medical background, can give you safe information about. Rule out the medical diagnoses first, and then you can explore this as a curious emergent phenomenon first if you wish

Take care,
Olivier