It's a problem that the BoC have tempted (and much succeeded) to get rid of. In the "good'ol time", when the notes were put strictly in order from XXX****000 to XXX****999, when one looked to the first note, he was almost assured there was a least a radar and often a repeater note, and even could tell which kind of radar the brick hold (as well as any other interesting number).
But since the new way the printers (CBN and BAI) put the bundles together by mixing thoroughly the notes from differents ranges, in short and long sequences, I really don't figure how any employee, guard, banker or cahsier can tell, just by looking on the first note in a bundle (whitout opening it), that this bundle have a radar (or any collectable serial number) in it. He must go through all the bundle just to be sure that there is a radar note in it...It's almost impossible to tell if a given bundle have a radar note in it (unless the first note is a radar...), just by looking at the first note, since there is no assurance whatsoever that the next note is from the same sequence, nor if the sequence continue for all the bundle...
The majority of the bundles have often 2 sequences of serial numbers, sometimes 3, even 4 sequences...(the number of consecutive notes is very variable).
If you look on the first note from a sealed brick, there is no assurance that the brick hold a collectible number. I got many sealed bricks and since the bundles are mixed-up, I got many times an "empty" brick, i.e. a brick (that I paid for) absolutely devoid of any radar, repeater or any interesting note...But you can also get a brick with 2, 3, 4 radars or even more in the same brick. Overall, on a large number of bricks, the odds tends to equalize and you'll find that, on average, there is one radar note per 1000 notes...exactly the proportion one can calculate from the numbering sequence.
So, unless the guard (employee, banker, etc) have time to loose and have the possibility to scan through many bundles in hope to get the interesting note (during his duty time), I don't believe that there is as much radar notes pulled out by the bankers or guards as before (about 5 years ago). The BoC have cut much of this speculation. We can't eliminate the possibility to get a good number by pure luck, but the chances are now the same for all of us.
Someone (a bricker for instance) may complain that the chances to get a collectible number from a brick are drastictly reduced since the new method, but the chances are more equal for all, including the bankers and other peoples which get theirs hands on the fresh notes before the others...They don't have time to spend to search through bundles whitout having a serious chance to get a good one...
If you find that there is less radar notes as before, it's maybe because the chances are now really 1/1000 to get one...getting a brick or not.