Picking entries left to right and skipping blanks

In the example attached, I have formulas which pick the entries from the "red" columns, one by one left to right (skipping the blanks), and when there is no more entries, the formula goes back to the beginning and picks the entries in the same order again.

For example:
_ 1 _ 2 = 1212
_ _ 1 _ = 1111
1 _ 2 3 = 1231

I need the same but with SIX columns. Can someone help me do that, using similar formulas or somehow "spreading" the idea to two more columns?

For example:
_ 1 _ 2 _ _ = 121212
1_ _ _ 2 3 = 123123

Thanks in advance