<Snipped quote by Raineh Daze>
Not to be rude or anything, but it's pretty dismissive of other people's hard work to just disregard what they write out of hand. It also tends to go badly for everyone involved. I would know - I used to just skim other people's posts and ended up not really knowing anything about who I was dealing with or what was going wrong, which caused problems for everybody.
Even reading a full chapter of an average novel these days doesn't usually take more than 15 minutes. Reading a tiny excerpt from one scene of a roleplaying equivalent takes even less time than that. Saying that it's "too long" or that it would "take too much time" is just disrespectful to people who are trying to work with others to create a shared narrative.
2,000 word co-op posts that would take half an hour to read carefully and block anyone else from interacting even when it's logical that it could happen tend to sour you on the entire concept. Particularly when they go against any idea of a shared narrative. That and I've met people who try to push them in every conceivable situation. That's less roleplaying and more a round-robin story by that stage. :/
As for the summoning thing, most people won't be summoning at the same time anyway. Take F/SN: Rin summoned three days before Shirou, Lancer was around even before that, Berserker and Caster were summoned long before even them.