Why are some Beleriand wars longer than others?

[Turin_Turambar]

War of wrath lasted 43 years. Dagor bragollach lasted about 2 years. Nirnaeth arnoediad lasted 6 days. Dagor-nuin-giliath lasted 10 days. Siege of Angband lasted 400 years. But during the siege of Angband there were no serious events that could be called war. So it was just an act of containment. One of the longest battles in war of the ring, the battle of hornbug lasted 1 night. The battle of the pelennor fields lasted about 2 days. The siege of Gondor lasted 1 day. The interesting thing some battles of beleriand like dagor aglareb, fall of gondolin, battle of lammoth, and battle of tumhalad pretty much the same length with battles in war of the ring. what i don't understand and wonder is why some battles in battles of beleriand took so much longer than other battles of beleriand and battles of war of the ring? I don't think the reason for this has anything to do with army population. Because Tolkien never made a clear statement of the number of armies in First Age and Third Age Wars. I think it's because elves can fight longer because they're immortal that some of the battles of Beleriand are this long? If you have information about this subject, please explain. Or you can share your own ideas.

 

[Uthalin]

"Battles of" mean different things. The Battle of Waterloo lasted a day, The Battle of Stalingrad lasted 6 months.
However I think that the main reason for the odd timescales is Mr Tolkien was writing a mythology, not a history. Similar things happen in early "king" lists for many cultures. I've not read the Bible for years but I remember some of the early dating was a bit screwy.