For single bus trip, it was on route 61 from Ngee Ann
Polytechnic to Eunos on a B10M MkIII on the eve of Chinese New Year
in either year 2000 or 2001; 3.5 hour journey due to jam at China
Town and Ubi/Eunos area.
I think I boarded the bus at around 10am and reached home at
1.30pm or thereabouts.
For a transfer-trip using the 'manual' SBS Transit farecap, it
was about 6 hours 19 minutes according to my records. Spent $5.71
and got back $3.81 in refund.
For a transfer-trip using the current $1.94 fare cap, it was
about 4 hours in total and I've done a few of these type of rides,
mostly with riding route 61 from Bukit Batok to home as the last
bus ride before the 2-hour fare expiry. I may be able to hit almost
5 hours if a peak-hour full-trip on route 858 was taken as the last
bus ride, but I have yet to do this.