A lot of the issue here comes down to the realities of getting big things built and that anything underground always involves some element of risk that geology isn't as expected.
Looking to the past, the various state electricity authorities did have a pretty impressive rolling construction program but there's a key to making that work - everyone doing everything all at once. Investigation people were always investigating and keeping well ahead of design people who were always designing, following on were construction and following them were commissioning engineers. So you'd have a lot of different projects all at various stages - some being investigated, others being designed in detail, some being built, some being tested and put into operation.
That "production line" approach is how the utilities kept up such a pace of new plant construction. People with specialist expertise who moved from one thing to the next and that even reflected in the actual construction - it was a case of building multiple things at once, at different stages. It wasn't a case of build one then build the next as that's too inefficient.
The whole thing had a lot in common with car manufacturing for example. Each person keep doing the same thing and at the end of the line is a constant stream of finished cars being completed. Most of those involved only saw a piece of the process however.
Go back to that approach and it could be done a lot more rapidly than 80 years. It'll still take years, but not 80 or anywhere close to that.
As a random example of how that works, I'll go back 55 years to 1968 and note what was happening at the time:
SA:
Closing = Osborne A station, in service since 1923 and now at end of life.
Commissioning = Second unit at Torrens Island A station (oil-fired steam) and official opening (ribbon cutting) of the station.
Construction = Units 3 & 4 at Torrens Island A (oil / gas fired steam).
Queued for Construction = Dry Creek (gas turbines).
Planning & Design = Gas conversion of Torrens Island A existing plant once the pipeline made gas available (1969). Plus to build a complete new Torrens Island B station and separate gas turbines at a site to be determined (ultimately built a Snuggery).
Tasmania:
Commissioning = Repulse, Cluny and Rowallan hydro stations. Plus the temporary gas turbines two at Bell Bay and one at Macquarie Point (Hobart).
Construction = Works underway on Lemonthyme, Devils Gate, Cethana, Wilmot, Paloona and Fisher (all hydro).
Queued for construction = Early works commencing on Gordon and Bell Bay (the latter being oil-fired steam, all others hydro) and ramping up as current projects were completed.
Planning & Design = Mackintosh, Bastyan, Reece (all hydro) and future projects under investigation.
Victoria:
Closing = Yallourn A after 44 years' service (coal)
Commissioning = 5th unit at Hazelwood power station (coal).
Construction = Units 6, 7 & 8 at Hazelwood. Works underway on units 1 & 2 at Yallourn W (coal).
Queued for construction = Units 3 & 4 at Yallourn W to be built when required (actual completion 1981).
Planning & Design = Newport D (oil / gas-fired steam) plus separately Loy Yang (coal).
And so on. Same for the other states, they all had a rolling program of investigating, designing, planning, constructing and commissioning new plant. That's what you need when individual projects take 7 - 10 years and you need to complete one every year, you do it by overlapping the stages in a production line manner such that there's constant work on each stage moving from project to project, and a regular set of new plant going into service.
Go back and look at the historic details and 10 year projects were completed every year. That's how they did it. In the decade to 1962, Victoria actually commissioned a new generating unit every 93 days on average and kept that pace up for the full decade - overlapping production line construction is how they did it. For the record the coal and oil plant built at that time is all gone now but the hydro they built is still in use today.
OK, so today isn't the 1960's but the same principles apply. It doesn't take a century to build ten things which each take ten years. No, you overlap them and the whole lot can then be done in about 20 years. That's how it was actually done historically.
A big part of the problem is the debate at the political and media level is dominated not simply by people who can't do it themselves but by people who've no idea how such things actually were done in the past. The idea that the one authority would have multiple project all at various stages, and that doing so was the actual key to success, is a concept they just don't grasp.