In the UK precision offset was used on the UHF 625 analogue TV network to minimise co-channel interference:
https://en.wikipedia.org/wiki/Frequency_offset The UK UHF network was meticulously planned to allow for 4 national channels covering 98%+ of the population. Channel 5 was shoehorned in much later and was always a bodge.
I'm not convinced we used precision offset on VHF in the days of 405 transmissions. I could easily be proven wrong if somebody finds a BBC or other document saying that it was tried.
Frequency planning in the UK has always had to be co-ordinated with France, Belgium and Holland. Again back in the says of 405 lines on VHF, viewers on the south coast of England were often troubled by interference from French stations. Usually in periods of settled weather when the troposphere would happily propagate Band I frequencies further than usual. Because the French 819 system used almost exactly twice the line scan rate of 405 you could resolve them on a 405 set but with 2 pictures side by side.
I assume other countries used similar offset methods. All now irrelevant in this age of digital TV.
PS: Searched BBC R&D reports and found these:
https://www.bbc.co.uk/rd/publications/rdreport_1962_19
https://www.bbc.co.uk/rd/publications/rdreport_1968_21
Pluse several more possibly relevant papers.
So the method was defninitely known in 405 days but I'm still not certain it was used in practice.