Since my trips through the I-84/684 interchange over the years only involved coming to/from the eastern end (to/from CT), which are likely done by the majority of travelers through that area;
287 WB approaching 684 only has a 1/2 mile advance, but I'm going to have to disagree with you on your assumption about the prevailing travel direction. While I'm not bothering to pull up actual traffic counts from NYSDOT/NYSTA/whoever maintains it now, based on the ramp configurations and my own previous travels through the area (which are numerous since I used to live down south and frequently visited family in northern CT) I would assume that the majority of traffic continues down towards NYC on the Hutch after passing 287, and that most exiting traffic does 287 EB -> 684 NB -> 84 EB and 84 WB -> 684 SB -> 287 WB. For example WB 84 to SB 684 has a flyover, whereas NB 684 to WB 84 has a tight loop ramp.
1. Traffic-wise, I was only referring to the I-84/684 interchange area per say and not the I-287/684/Hutchinson Pkwy/Westchester Ave interchange and was referring with regards to through-traffic beyond NYC as well as truck traffic (which is NOT allowed to use the Hutchinson Pkwy IIRC).
2. From your post "that most exiting traffic does 287 EB -> 684 NB -> 84 EB and 84 WB -> 684 SB -> 287 WB."
Outside of 684 NB-> 84 EB piece, aren't we saying the same thing regarding everything else? You're actually agreeing/supporting my earlier post.
3. As far as the ramp from 684 N to 84 E is concerned (Exit 9E); that ramp design was likely design oversight in terms of actual traffic counts. Outside of the flyover ramp to 684 S from 84 W; the interchange was designed essentially as a 'cookie-cutter' cloverleaf/flyover 4-way type as opposed directional 3-way expressway with an added connector (to US 6/202 & NY 22).
The entirety of I-287 is maintained by NYSTA.
While that's fine and dandy for I-287; that doesn't explain I-84 (particularly westbound). Yes, I'm aware of the short-lived period when at least the eastern-NY stretch of 84 was briefly maintained by NYSTA; but the 1/2 mile advance signage for I-684 issue from westbound I-84 not only predated that temporary transfer of maintenance responsibilities, it has also outlasted it.
The only I-684 interchange signage changes from westbound 84 I know of within the last 21 years was when all the overhead diagrametric signs were replaced with 2 identical ground-mounted signs along each side of 84 west and the replacement of the actual exit sign bridge w the exit and pull-through sign (for 84 west) with a single cantilever sign structure for only the exit. The sign panels at the ramp split were also replaced as well.
However, despite all the above-changes 84 westbounders STILL only get a 1/2 advance notice for I-684.