Normally 6-9 (Sunday length, 15 minutes shorter than a normal weekday), with Saturday 6-10 as normal, but not seen this years schedules to confirm. On weekends the 6am hour usually has two 15 minute pre-recorded shows and 7am hour has one, and on Christmas Day/Boxing Day/New Years Day most if not all hours will have a pre-recorded 30 minute show for the second half of the hour - hence why these days usually only have one presenter. (A couple of days are usually shorter on BBC1 due to Match of the Day being repeated, but continue on the BBC News Channel)
Will there be the odd situation on Wednesday 27th of the last regional news being at 0725 due to Match of the Day?
Yes and that happens every year, and I have to wonder why they bother doing regional news at all on those days as the audience at 0625/0655/0725 won't be sizeable.
It's also slightly odd that the Saturday one remains 4 hours long, even over Christmas and even in 2015 when it was Boxing Day, when everyone loses track what day it is so there is nothing different about a Saturday to any other day.