Noob friendly guide to sextant blocking and sextant usage

https://youtu.be/u35BiSZWSm. First of all this link video explains it really well I think but since one of my friends still didn't know anything after this video I will explain it in words for you new players out there .
sextants comes in 3 tiers : apprentice(white T1-5) journeyman(yellow T6-10) and master (red T11-15) and each can only be used in their appropriate tiers or below . First of all let's explain how a sextant works : by using a sextant like a normal currency item on your map that you want to use it on in the atlas you give that map and any maps within the sextant radius(red circle) an extra mod (there are many so I ain't going to list them here)
. This is simple enough . By having a sextant mod on a map none of the maps affected by that mod can now roll that on itself which is essentially sextant blocking . Simply put we will say for example T1 is the map you wanna get the good rolls on (extra monsters , breach whatever) and T2-5 are maps close enough to affect T1 and T6-10 touches T2-5 . To sextant block start as far out as to want or have enough currency for and apply to sextant (we will say T10 for example purposes)roll sextant on T10 until you get a bad mod that you don't want on T1 and never run maps that is Affected by that sextant. By doing this you have blocked that bad mod from rolling on whatever map that is in the sextant radius , if say T9 was in the radius that means you can now roll sextants on T9 and never get that blocked roll simply repeat this process untill you get to the maps that is near enough to affect T1 with their sextants. And there you have it how to sextant block.
Why do it you ask ? by sextant blocking you are effectively investing a initial sum of currency to permanently reduce your chances of rolling a bad mod . And therefore reducing the amount currency you use in the future rolling sextants .