About a year ago, when wacky rock duo Ween still had “that new-car smell,” as manager Patrick Jordan refers to the 90s indie phenoms’ reunion, the band’s Denver promoter called. “If you want to play Red Rocks next year,” he said, “you better start challenging dates.”

So in May 2016, Jordan contacted the City of Denver, which runs Red Rocks Amphitheatre in nearby Morrison, Colorado, with his choice of 2017 dates. Another act, represented by an agency (WME, CAA, Paradigm, UTA, ICM and APA all have robust music touring departments that work with Red Rocks), had already reserved them. Jordan requested a challenge, but he lost — the other act paid Red Rocks $15,000 to maintain its date and keep Ween away. In the end, Ween found a new date, this coming July 12, and sold out the 9,500-capacity venue in a day.

Doing all this so early caused anxiety for Ween, which hadn’t even begun its 2017 touring schedule. “We don’t book that far in advance, so that was taking a risk,” Jordan says. “They’ve just recently reunited, and we weren’t sure where it was going.”

Such are the politics of Red Rocks, where even the biggest artists have had to book weekends and other high-demand dates as many as five years in advance.

The picturesque outdoor amphitheatre is a rite of passage for scores of acts. With a stage that overlooks the Denver skyline and seating cradled by the Colorado mountains which house the venue, Red Rocks has been the place of legendary performances — from the Beatles in 1964 to U2’s career-making “Sunday Bloody Sunday,” used as the song’s official video (an MTV hit) in 1983. More recent runs include dates by Coldplay, Radiohead, Twenty One Pilots, and Eric Church.

“There’s nothing quite like being on that stage in the middle of some jam and looking over at your buddy and looking up at all these people and this monolith and seeing a moon and feeling almost like what I would imagine it would be like of being inside a painting or cartoon,” singer-songwriter Ryan Adams tells Variety. His June 20 headlining gig will be his third at Red Rocks. “And it sounds f—ing amazing there.”

Demand has surged recently: Red Rocks put on 73 paid events in 2010 compared to 155 in 2016. The concert business, meanwhile, is in a protracted boom, as artists have had to tour to make a living in an age of depressed record sales, and fans save the money they once spent on CDs to buy tickets and T-shirts. Legal marijuana in Colorado has prompted increases in local tourism and housing, and it’s not a stretch to suggest people who come to the state for weed are also interested in attending a Snoop Dogg show at Red Rocks.

“If you want a weekend date at Red Rocks, it’s very challenging to get,” says Don Strasburg, the AEG Presents Rocky Mountains co-president who has booked Red Rocks shows for decades. “So many artists who have such a long and storied history up there tend to grab the holds and want to come back.”

Red Rocks’ artist-booking policy is complicated and evolving. Until recently, artists could hold dates five years in advance. As of November 1, the city will reduce the advance-booking time to two years — at that time, an act will be able to hold a date in November 2019.”The competition for the dates, and people placing holds for dates that far out, when who knows what’s going to happen, didn’t make a lot of sense,” says Tad Bowman, the venue director who oversees bookings. Some artists have trouble with the lengthy advance notice, which is unlike almost any other venue in the world, because they time tours to album releases.

“Record cycles are really difficult,” adds Buck Williams, agent for Widespread Panic, a Paradigm client, which has sold out a record 55 dates at Red Rocks, including three in late June, as well as R.E.M. “‘I think we have an album out next April, and we’d like to be at Red Rocks next June’ — but you don’t know.”

Even more convoluted, and expensive, is Red Rocks’ date-challenging procedure, which Ween, Widespread Panic and others have employed. Just about anyone can book an open Red Rocks date, but another agent can storm the date and force the original performer to put up money to hold it. The first act then can choose not to pay — and lose the date.

The challenge policy, a sort of high-end insurance against artists’ uncertain schedules, is not an uncommon practice for venues, but the “cash-to-hold” deposit process employed at a coveted venue like Red Rocks, is. “It does complicate things,” says High Road Touring’s Frank Riley, agent for Ween, Dispatch and Ryan Adams, all playing Red Rocks this summer. “We’ll book a Red Rocks show in conjunction with a presumptive release, and the record gets delayed a month or two. What do you do? You have to hand back the $15,000.”

Navigating the hold-and-challenge process is far easier with the help of experienced agents and promoters. Jordan, the Red Light Management veteran who represents Trey Anastasio and Gogol Bordello, and co-manages Phish, says AEG’s Strasburg and Live Nation’s Eric Pirritt, who have been locked in Red Rocks booking wars for years and promote almost all the big shows, are “intuitive, and they’ll nudge us if they feel like, ‘OK, you need to get going on your 2018 dates right now if you want to get any day.'”

Adds Live Nation Colorado president Pirritt: “There’s no exact science. Calendar management is a big part of the promoter’s job. Directing traffic is a lot of what we do.”

Some iconic venues, including the Hollywood Bowl, the Greek Theatre and SummerStage in New York City, require bookings months ahead of schedule, but agents and managers say Red Rocks’ policy is the most extreme of any venue in the country – and it’s worth the extra effort. “We’re normally booking shows a year or 18 months in advance anyway,” says Paul Crockford, manager of Mark Knopfler and co-manager of Paul Simon, who returns to Red Rocks June 28. “Everywhere else is second best. We’d hate it if we can’t play there.”