Time is a unimportant aspect of Lost. While Lost deals with many metaphysical and philosophical things, Time is not one of them. Darlton have stated on several occasions that time - timeshares - the song "Time after Time" - The Land before Time - Time Magazine - or time traveling would never ever be a major focus of the show. Darlton lied.
See, Tim Kring had a show called Heroes. And Heroes had a lot to do with time-travel. So, after the "Stranger in a Strange Land" incident, Damon and Carlton were watching Heroes one night and decided a good way to get back at Kring was to kidnap his family. Damon thought this was a bit extreme, so instead they wrote Season 5.
Season 5 took time-travel and was like ZOMG PWN EPIC WIN and totally ruined Heroes, because now the people at large realized how sucky Heroes' concept of time and time-travel really was. This made evident by the "Faraday > Nakamura" bumper-stickers that have become quite popular amongst media consumers.