More or less. The BBC local radio stations in any case started life in the 60/70s, as city/town based, rather than county. When the second phase launched in the 80s, they were all county based, Norfolk, Suffolk, Devon, etc
although there were still naming anomalies. BBC Radio Northampton for instance, rather than Northamptonshire. The coverage was increased from city to county for the legacy stations, Derby, Leicester, Nottingham, Newcastle etc. There are of course stations that straddle counties, BBC Solent, Sheffield, 3CR (that stated life as Bedfordshire)
Therefore there are areas that for technical and geo-political reasons have no BBC LR service. Cheshire and Dorset being the two prime examples.
Dorset does have an opt out, or at least it did (not sure if it still does)
I think with Cheshire the main problem is that it is surrounded by three of the big early established city stations: Manchester, Merseyside and Stoke. Radio Shropshire to the south has a big enough patch as it is and on the other side is a national station, so no potential to extend them to cover the county.
Staffordshire is in a similar situation, it does have Radio Stoke within it, but the rest is split up between WM, Derby and Shropshire. It also straddles two TV regions.