Most of what goes wrong in a shower is a sequencing failure rather than a workmanship one. The materials were usually fine. They were covered before they were ready, or a stage that would have proved the assembly got skipped because the tile was already booked. The order is not a preference — each stage depends on the one before it having cured, and none of them can be none can be reshuffled to suit a calendar.
The flood test is the checkpoint everything else rests on. Once the waterproofing is complete and cured, the drain is plugged, the floor is filled to just below the top of the curb, the water line is marked and it is left standing overnight. A drop in that line, or a damp patch appearing on the ceiling below, is a fault found while the fix costs a morning. The same fault found later costs the tile, the glass and the wall as well. It is the cheapest hour in the whole build and the one most often traded away.
Cure periods stack up behind it. Waterproofing cures before it can be tested, adhesive before grouting, grout before silicone, and silicone before the shower is run. Each is roughly a day at ordinary indoor temperature and longer in a cold, damp room — which describes most unheated bathrooms on this coast in February. Together they account for three or four days in which nothing visible happens.
Two fixed points sit outside that. Where the scope requires a permit, the plumbing rough-in is inspected before the walls close, so the waste, the vent, the valve and the blocking for glass, grab bars and a bench all have to be correct at that moment rather than adjusted afterwards. And glass is templated against finished tile and then fabricated, which puts a gap between the tiling finishing and the enclosure arriving. Both are predictable and belong in the schedule.