TV networks are no strangers to spring cleaning, as this is traditionally one time of the year when renewals and cancellations are announced. But the process typically takes on different forms depending on the show and the network it airs on. Broadcast TV and cable have wildly different business models, leading to hugely different renewal and broadcasting practices.

Case in point: NBC’s fledgling new drama Parenthood has been picked up for a second season. After airing only a handful of episodes, the mid-season replacement dramedy got the greenlight for another season thanks largely to its clever writing that avoids cliches and an appealing cast full of actors that play off of each another with family dynamics that ring true.

When you move away from broadcast networks, things are a lot less structured. Shorter seasons and fluid time slots are quite common, because those networks can afford to change things up; audiences will follow quality shows wherever and whenever they pop up. Shows like HBO favorite Curb Your Enthusiasm, which just coaxed creator/star Larry David into signing on for an eighth season. The show’s lauded seventh season — which reunited the cast of David’s other creation, Seinfeld — ended in 2009, but the eighth won’t air until sometime in 2011. That’s a two-year gap, which would be unheard of on broadcast TV, but is a luxury cable can afford.

Similarly, FX has announced that Rescue Me will return for its sixth season on June 29th. The Dennis Leary vehicle hasn’t dealt with a lot of scheduling issues, but it’s been able to air seasons that are dramatically shorter than those on broadcast TV. Most of the show’s seasons have had a mere 13 episodes (lower episode orders arguably lead to higher quality episodes, but that’s a whole other topic). The show’s return for Season 6 was never in question, but the announcement came with some much bigger news: 2011’s Season 7 will conclude the show next year.