How can shows like Roseanne be on TV Land as well as LAFF and MASH be on WGN America and METV? Is there seperate rights for cable/broadcast? Why can some diginets not acquire newer shows then like from 90's/00's?
When something goes into syndication, you get what they sell you. The typical unit is a season. Most shows are sold only in sequence and you don't get to pick and choose which episodes to play or the order.
Whomever pays gets to play it but they have to play it according to the terms of their contract. For example, you can't buy rights to a show and create your own marathon. If you want to show a marathon, you have to buy a marathon.
The syndicator sells the rights to a particular property. The syndicator can sell
1) Exclusive Rights to any one entity. This means that no other broadcast, cable, satellite, or streaming service can program that show. This is ubber expensive and rarely ever done with reruns.
2) broadcast rights (over the air). This is generally done per TV market and the buyer generally gets exclusivity within that market. This means that no other broadcasters (even those rebroadcast on cable) can show the program within that market. This does not usually include national cable channels. Only out of market TV stations are affected. This is where "syndicated exclusivity" (SyndEx) bites "super stations" in the butt.
3) cable rights (National cable channels). The rights to cable can be sold as exclusive, or non-exclusive. Obviously buying the exclusive rights is much more expensive. Once again "Exclusive" in this context means that no other national cable channel can show the same program. It does not generally mean that the one cable channel is the only place you can get the program.
4) Streaming rights (Things like Amazon, Netflix, Crackle, Hulu, etc). This can be either exclusive or non-exclusive. Once again, exclusive in this context would be that no other streaming site would get the program. This is why local channels can only stream their news and locally produced programs on their web sites and usually can't stream their channel 24-7
The syndicator has control of how the program is doled out. As mentioned by harshness, usually the syndicator dictates what episodes will be aired which days. But if the syndicator just sells you a library of episodes you may have the ability to play whatever episodes you want in whatever order.
So in short, it is 100% up to whatever the contract between the syndicator and broadcast/cable/streaming entity says. And it can pretty much say anything.