Following retirement, I have for interest, used by 40 years planning experience to produce a series of level 1 schedules in excel covering a typical $300/400M Process Plant, built within a refinery complex, based on Owner's Board investment sanction PM methodology stages (FEL/FED), from inception to Owner' production and Pay Back (Timeline Options, Proposal, Concept, BEDP, EPC, OpReadiness) based on JV contractor using a OoC/IC design and procure split and local IC build partner.
These were typically used to stimulate discussions in the project team as they could be produced very quickly at the start of any project stage unlike the level 3 P6 schedules which took weeks of effort.
If anybody wants a copy to look at (and comment on) send me a message with email address