To add to my earlier post Toronto is quite backwards in how they do subway work and overly cautious.
Even in Budapest, Hungary right now they have shut down a large portion of their Metro 3 in the centre of the city to rebuild the stations, track, etc. They have been doing this for the past 12 years with Metro 2 being done from 2006 to around 2011. They closed portions and rebuilt them for extended periods without worrying about shuttle capacity etc.
See here:
https://bkk.hu/en/news/2020/11/trav...-of-the-middle-section-of-metro-line-m3.5957/
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In 2017 when I was in London they had a section of the Central Line shut down for station works and bypassed stops for weeks at at time (not just weekends and overnights)
The point I am making is that it can be done but the TTC does not have the backbone to do it.