It is not only in March that timetables of regular trains may be revised.
HyperDia sometimes does not reflect new timetables by the date of the revision.
(a) JR-Hokkaido will revise its timetables on 30 August 2014, within 10 days from now.
(b) Some JR railroad operators offering Haneda Airport [HND] and/or Narita Airport [NRT] accesses may revise their timetables in October. (They did in October 2013.)
: Keisei Electric Railway and Hokuso Railway lines (including Narita SKY ACCESS).
: Toei subway Asakusa Line.
: Keikyu lines.
Regarding (b), I do not recommend relying on HyperDia about timetables for these lines when you plan your November journey.
You can estimate your time required for traveling between HND / NRT and some major stations and destinations by checking japan-guide.com articles.
http://www.japan-guide.com/e/e2430.htmlhttp://www.japan-guide.com/e/e2027.htmlWhen you search for routes and traveling time to major tourist destinations, I recommend you check related japan-guide.com articles before relying on route-finding tools.
Route-finding tools such as HyperDia and Jorudan answer routes which are logically possible, but they are not always practical or suitable for specific passengers.
HyperDia, under some conditions, answer roundabout routes (e.g. turning back needlessly to use Shinkansen).
Jorudan is regarding some stations in one area as the same even though their gates are located a little apart (e.g. Namba, JR-Namba and Osaka-Namba Stations).
JR-East is offering on its website timetables of its Shinkansen lines and some of its Ltd. Express trains.
http://www.eki-net.com/pc/jreast-shinkansen-reservation/english/wb/com...Regarding Tokaido Shinkansen (Tokyo -- Nagoya -- Kyoto -- Shin-Osaka, operated by JR-Central) and San(-)yo Shinkansen (Shin-Osaka -- Okayama -- Hiroshima -- Hakata, operated by JR-West), JR-Central is offering on its website timetables of regular trains (i.e. trains except extra trains).
http://english.jr-central.co.jp/info/timetable/index.htmlThese timetables of JR-East, JR-Central and JR-West may be revised in March.