Heroes, Grey's Anatomy, Lost etc. buy seasons now or wait for the complete sets?

[Marquoz]

Something like Heroes which may last a while, it's better to buy seasons at a time, there's no point in waiting 5-10 years until the complete series comes out. Lost which is nearing the end of it's run, it would be better to wait, and get the entire thing all at once.

My experience was Stargate, I bought them as they came out starting with season 1, it wasn't until 10 years later they came out with the complete series, so there was no point in me buying it. MASH on the other hand, was long since done, I had bought only a couple of seasons before they came out with the entire series, so it was worth me getting the entire series.