Search coil selection

I like to use various types, shape and size search coils to help me winkle out what I'm am searching for at search sites. 
This is one of the reasons I use a Minelab CTX 3030 or Minelab Equinox, they have a wide range of accessory search coils. 
A couple of times this year Ive been in very good metal detecting situations away from home and my choice of one single search coil to travel with was probably not the best choice of search coil for the area. 
I did ok as in detecting and recovering very cool finds, but I know I could and should have done much better, dont worry I will not make the same mistake three times lol 
Leaving potential good finds in play happens when you are not using the correct search coil for the area or intended targets, most problems connected to search coil selection have to do with using the wrong type, shape or size search coil.
For example, using a large search coil at a very trashy site or searching for targets known to be shallow is not the best option.
You will suffer from both iron and target masking using a large search coil at a trash infested site.
A small size search coil is not the best choice at a site when searching for older coins or artifacts that are often only detected in deeper levels of sand or soil. 
Assuming the area isn't too trashy, you gotta go big or go home empty handed. 
The type of search coil could also be a problem, for example using a mono type search coil in a heavily mineralized area, where a double-d type search coil is a better choice because they are not effected by difficult ground as much as mono search coils.
The low beams in foggy conditions analogy best describes using a double-d search coil over difficult ground.
On the flip side, a mono search coil with its deeper inverted cone or bowl detection field will punch deeper over less difficult ground, horses for courses is another analogy Ill throw out there. 
Typically the search coil that comes with your metal detector is the best average search coil for your metal detector, meaning it is considered to respond to the widest variety of targets at a good variety of depths.
You play the percentages using the search coil that came with your metal detector, speciality type or size search coils in all types, shapes and sizes serve a speciality search agenda.
I always tell people thinking about buying a new metal detector to think about buying a different search coil for the metal detector they have before giving up on their metal detector as search coil selection could make a difference.
A metal detector not known to be the deepest seeking can be transformed into a deep seeking beast using an extra large accessory search coil.
A metal detector known to have a slow target recovery speed in trashy areas can be transformed into a killer trashy area unit using a small six inch sniper search coil.
Small size search coils lack target depth but because they read less ground and other metal objects around them they excel  as sniper coils, detecting high value targets an 11-inch search coil user probably wouldn't have a chance of hearing.
The difference between going home empty handed or with a top pocket find often has more to do with search coil selection than being in the right place at the right time.
When you know you are in the right place it pays to have the right search coil on your metal detector.
Note to self, extra search coil, extra search coil, extra search coil, extra search coil!