Every radar has blind spot thats why no air defense is 100% kill shot.
A missile flying at 30 metre can only be detected from less than 30 km max, if there is a clear line of sight and that is without accounting for mountains, valleys and clutter. Nirbhay and tomahawk can go even lower
You are not aware of many things.
A radar is mounted on top of a tower to increase the radar's horizon. And we have such tower mounted radars. So does Pakistan.
But we also have aerostat mounted radars. They are at a height of around 1500 ft. They can be deployed even higher. We can see far out into Pakistan with the help of these. PAF at present doesn't have such a capability.
As for blind spots, every radar has them. That's why you have radars of different bands deployed with overlapping coverage. You have a multi tiered over lapping radar coverage and Sam fields.
No one in their right mind deploys just a single radar.
And as for using valleys and mountains, this is where LLWR comes into play. Bharani and Aslesha are deployed on some summits and in areas overlooking valleys and passes.
IAF doesn't leave anything to chance. Everything is planned for and taken care of. Indian Army does the same. Every scenario is thoroughly wargamed and measures aretaken to plug various gaps. There isn't any scope for complacency.
Unlike the PA and PAF we don't believe in fake bravado and we don't take pride on our vaunted superiority unlike our counterparts on the other side of the border . We meticulously plan for every contingency after taking a plethora of variables into account. Everything is checked and rechecked.
NOTHING IS TAKEN FOR GRANTED.
Also do watch some videos of JLENS from Raytheon.