Faster expansion (both planning and construction) comes out of several things.
1) Consistent, forward, planning. (you need to know what you're going to build not just today, or next year, but 10 years from now; that allows alot of the planning, design, consultation, testing (soil, water table etc.) to be done long in advance.
2) Continuous build. As
@allengeorge notes above, this is about institutional memory; but its also about re-use of existing equipment, and reducing staging time etc, as
@ARG1 notes.
3) Extensions over new lines in many cases. Extensions of existing subway or LRT can generally be opened in small segments or even one station at a time. We tend to treat these things as mega-projects and build it all at once, and open it all at once.
That is necessary if building an entirely new line............but, for instance, if we chose, we could be putting all our effort into the SSE going north from Kennedy and open a Lawrence Station within 3-4 years, followed by Scarborough Town Centre 2 years later and McCowan the year after that. Likewise, Yonge North could go to Cummer in 3 years, easily, and to Steeles in 5, then keep going north until we reach a point where we really want to stop.
4) Employing both planning and construction management practices that can expedite delivery. Beyond going above-grade/elevated/trenched etc, where possible; the use of cut-and-cover, shallower tunnels/stations (which is very do-able, can shave 25% off construction time/cost; as well as 24-hour construction and larger labour pools. That last bit can drive costs up (paying shift premiums); but also saves time, which is money.
5) Not over-building stations; aside from depth, we tend to build stations that are too large by any reasonable measure. Its true that Line 1 and portions of Line 2 were really under-built from a capacity growth point of view; but we've gone to the opposite extreme. This, I think, is partially predicated on the slow nature of network build-out. ie. If you knew that Relief/Ontario Line would reach Steeles within 10 years of Line 1 being extended to same; you might choose to build a much smaller Steeles Station, as it would have a significant portion of its passenger load shifted to the east.
6) Lastly, on consultation, we really ought to streamline, not to cut out meaningful consultation, but to cut out meaningless consultation.
Truthfully, most consultations have next to no impact on whether something will be be built, or what route it will follow.
That's not what consultations are about, whatever we pretend. Politicians, and sometimes, if you're lucky, planners get a say on those high level decisions.
Consultations, in reality serve only 2 purposes, one is mitigation, the other is window dressing; what would the community that will be disrupted by years of construction like as compensation for their trouble? ; and what theme/colour etc would you like in your new station. There is a periodic benefit of consultation when knowledgeable people point out obstacles or problems to planners in advance, which can save money and hassle, but that's incidental, most often.
If we cut consultation back to what's really on the table to change, it saves us all lots of time and money.