@feliciarabbiton Assuming some of the longest trips on each line (Epping to West Ruislip, for example) it'd come to somewhere between 8 or 9 hours (7 hours 44 minutes if you never have to wait). That would get all five lines in with some bus journeys and a trip from Morden to Startford using the Croydon Tram, the Overground, and the Elizabeth line.
@feliciarabbiton I'd have liked to put the DLR in too but that may be a bit too much.
@feliciarabbiton Epping to West Ruislip on the Central Line.
West Ruislip to Uxbridge via Bus.
Uxbridge to Cockfosters on the Picadilly line.
Cockfosters to High Barnet via Bus.
High Barnet to Morden via the Northern line.
Morden to Stratford via Croydon Tram to West Croydon, Overground to Whitechapel, Elizabeth Line to Stratford.
Stratford to Stanmore via the Jubilee line.
Stanmore to Harrow & Wealdstone via bus.
Harrow & Wealdstone to Elephant & Castle via the Bakerloo line.