Well, Wales and the West of England are the only (?) ITV1/ITVplc regions at the moment that don't use an alternative title for the 6pm weekday show. (e.g. Meridian
News
/ Meridian
Tonight
etc)
So, introducing a 6pm-specific title would be more in keeping with the other ITVplc regions.
I'm sure there was a period in the 1990s when 6pm-specific names were used: (Wales = HTV News / Wales Tonight. West = HTV News / The West Tonight)
The two regions' programmes had a similar look to each other during that period (an "HTV generic news look", if you will).
Outside of that period, I think the West edition had only ever called the 6pm show the exact same thing as the bulletins - i.e. HTV News.
But the Wales edition had used the 6pm title "Wales at Six" in some pre-"Wales Tonight" era.
It used to be called Wales At Six and then in 1994 they moved it to 6.25pm and renamed it Wales Tonight. In 1999 it moved back to 6pm and was renamed HTV News on both West and Wales.
On West I remember the main 6pm programme being called HTV News in the early 1990s although it was called The West Tonight for a time.