It's coded in, if you can read the code you can predict days when the boss spawns and for some bosses, which location it will go to. You can do this and predict within 3-5 day period when it'll spawn. It get's technical, I have over 100 encounters logged on notepad in Unitera alone since the September before last years(2013) logging. There is a pattern
For example, Midnight panthers and Man in the Cave on Unitera.
"October, 13th(2013) - Midnight Panther, South Spawn. ~ Tamed
November, 19th(2013) - Man in the Cave. ~ Empty
March, 17th(2014) - Midnight Panther, South Spawn. ~ Empty
April, 22ed(2014) - Man in the Cave. ~ Fur Cap
April, 29th(2014) - Midnight Panther, East Spawn. ~ Panther Paw"
None until the release of the unblockable spawns. It also seems some bosses have had their spawn times increased.
"September, 7th 2014, Midnight Panther, South Spawn. ~ Empty
September, 27th 2014, Midnight Panther South Spawn. ~ Empty
October, 12th 2014, Man in the Cave. ~ Merc Sword
October, 21st 2014, Midnight Panther, South Spawn. ~ Panther Paw
November, 30th 2014, Man in the Cave. ~ Empty
December, 21st 2014, Midnight Panther, South Spawn. ~ Empty"
Originally Posted by Veela
It's coded in, if you can read the code you can predict days when the boss spawns and for some bosses, which location it will go to. You can do this and predict within 3-5 day period when it'll spawn. It get's technical, I have over 100 encounters logged on notepad in Unitera alone since the September before last years(2013) logging. There is a pattern
