Why are there 6 gear values for FD fine-tuning? What do they mean?

Gear 1st: Press and hold left shifter — FD moves from small to large chainring.

Gear 2nd: FD on large chainring, RD on smallest 6 cogs — fine position value.

Gear 3rd: FD on large chainring, RD on largest 6 cogs — fine position value.

Gear 4th: FD on small chainring, RD on smallest 6 cogs — fine position value.

Gear 5th: FD on small chainring, RD on largest 6 cogs — fine position value.

Gear 6th: Press and hold left shifter — FD moves from large to small chainring.