Let me use A B C and D since they imply order. Where A is a Genesis fur STARTER and B, C and D are not Genesis. The possibilities are
Ab x Bb => Ab (case 1) Ab (case 1) Bb (both case 2 and case 3 unknowable success) Bb (both case 2 and case 3 unknowable success)
Ab x Bc => Ab (case 1) Ac (case 1) Bb (both case 2 and case 3 unknowable success) Bc (both case 2 and case 3 unknowable success)
[ The above two can be avoided by ensuring the shown B on the chosen mate is RETIRED. ]
Ab x Cc => Ac (case 1) Ac (case 1) Bc (case 3 success) Bc (case 3 success)
Ab x Cd => Ac (case 1) Ad (case 1) Bc (case 3 success) Bd (case 3 success)
[About half the time a mid-level showing mate will be one of the above two cases. Why? if C is the mid-point it's 50/50 the hidden will be more dominant, hence is B]
Ac x Bb => Ab (case 1) Ab (case 1) Bc (case 2) Bc (case 2)
Ac x Bc => Ab (case 1) Ac (case 1) Bc (case 2) Cc (case 3, unknowable success)
Ac x Bd => Ab (case 1) Ad (case 1) Bc (case 2) Cd (case 3, unknowable success)
Ad x Bc => Ab (case 1) Ac (case 1) Bd (case 2) Cd (case 3 unknowable, breed back to Ad for 1-in-4 Dd success)
I've eliminates redundancy such as "Ab x Dd" since this is identical to "Ab x Cc"; or "Ac x Dd" which is identical to "Ab x Cc".
Your question has to do with the unknowable outcomes (Cc and Cd, in the lines above).
Avoiding these two cases is why many recommend going as deep as possible.
I suggest that half the time, you're wasting your deep fur mate because you won't get these cases. If you get an offspring showing recessive to the mate (the Cc and Cd outcomes, above), then you should switch to your more deeply recessive options in the hopes of eliminating the unknowable (Cc and Cd) outcomes.
Gee, I hope I'm done refining this post
