Google Maps and Citymapper produce much more realistic journey times than other tools when one always catch the first train towards the desired direction.
Vauxhall is a much easier change than Waterloo. If the train stops at Vauxhall, I'd rather prefer taking the Victoria line there than boarding at Waterloo unless boarding at Waterloo can save me a change. Moreover, Vauxhall is in zone 2 which delivers cheaper fare as well.
Similarly, I prefer changing at Clapham Junction for long distance trains because it's also an easier change than Waterloo. I prefer Overground - Clapham Junction compared to Jubilee - Waterloo, because the Overground and Clapham Junction are nicer than the Tube and Waterloo and they avoid zone 1.
Journey planners take account into the interchange station. They choose the one with the easiest change to minimise journey time. For example, Vauxhall compared to Waterloo.
And nothing stops you to take the first train along the route Google Maps provide. I generally do that, once the fastest route is obtained, I travel immediately on the route provided.
Hello there. I'm not familliar with Citymapper, but I must regrettably disagree about googlemaps, when it comes to making journey within London by public transport. I've seen several recommendations by googlemaps and it does very much in my view create unneccesarily complicated journey involving more changes than is desirable, working on an assumption that ever bus, tram, tube train will be precisely on time. A lot of the punters I have to advise will be nowhere near as familliar with getting around London as you (and me) are fortunate enough to be, and I find myself having to advise them to make their journey a lot simpler than google maps would recommend.
As for your points regarding Vauxhall, well with respect, what works for you (who I presume resides in outer London or close by maybe,) simply would not work for the punters that I have to advise. Changing at Vauxhall is great on the way out if there is a direct train to the final destination, but in cases where it then also neccesitates an additional change at Clapham Junction, I don't think that is good advice for the regular passenger. I appreciate it works for you and it would probably work for me, but I do deal with passengers who aren't as au fait as you and me in getting around, and may well be carrying luggage. That is not to insult the intelligence of the passengers, but it is worth noting that in most cases they won't be as familliar as you, me or most people on this forum, with getting around. I long ago came to the conclusion that they are better advised to travel via Waterloo. What I probably didn't make clear in my earlier post, is that the passengers I deal with are not only possibly unfamilar with making these journeys, but are also commencing their journey at a station which will require them to travel into London and then cross over to either Waterloo or Vauxhall. It really is better for them to avoid having to change again at Clapham Junction. I do think Vauxhall is a better interchange when travelling into London as one doesn't then have to wait on the platforms in that scenario. And as I said before, I certainly advise against, when practically possible, doing a journey which involves waiting around on the platforms on a cold dark evening at Vauxhall. I do take on board your points about avoiding Zone 1. That is a very good point. And obviously relevant to yourself and other people who make similar journeys, but I'm afraid it isn't relevant to virtually all the punters that I have to advise about changing onto SWR trains as they will have started back from a station a long way out to London. .
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And nothing stops you to take the first train along the route Google Maps provide. I generally do that, once the fastest route is obtained, I travel immediately on the route provided."
As for the last point, I do agree with you about nothing stopping them catching an earlier train, yes you are quite correct on that and I do tend to encourage people to get the first available train to the interchange point, mainly because the interchange station almost always offers a pleasanter waiting enviroment. Especially in the colder months of the year.