a friend of mine bumped into one of the contestants from series 1, contestant seemed to imply the time gap at the end of a leg is not necessarily the time gap they send you out when the next leg gets going, they just close it up, in 3 series no pair has won by a day or more, which you'd think could easily happen after 50 odd days, although I haven't watched the final episode of the current season, but seemingly not
Just wished they'd choose some more experienced travellers as a fresh up, the current contestants 🙄
The issue with the time gap between legs is that if you arrive at the end of a leg anytime between say 9am and 3pm, you start the next leg between 9pm and 3am which is a bit useless as there are often limited transport options at that time unless there happens to be a nightbus. So you can get in with a decent lead but see that effectively evaporate when you have to hang around for a bus, or (as happened in this series a few times) find another hotel to sleep in, which you have to pay for, whilst the others are still snoozing for free in the posh paid for one. Of course it could happen the other way but I think in practice this can naturally truncate the legs a bit.
Then you've got various legs which are wholly dependent on contestants getting a particular train or boat. Thinking of that one across the Caspian in the first series or the train up to Churchill in this series. You can get there 8-10 hours early but there's only one service a day so other teams can massively catch up.
I think there are other ways the production company may try to nudge or intervene to ensure a close race but by and large with the budgets they have they're all likely to creep along a bit, and all the jobs pay roughly the same.
Not sure about more experienced travellers. Part of the fun of the show is seeing normal people go on an adventure and thinking "I could do that" or often "I would have done that better"
They also want the show to be about experiences as much as the race, people who haven't had opportunities or adventures like this brfore. Seasoned travellers probably wouldn't be going hundreds of miles out of their way for a plane ride or to visit Niagara falls