Back in the 70's-90's of my experience, it was all by the needles, ILS into ABZ, NDB approaches to the rigs, I even managed a VOR approach to Kirkwall in the Orkneys once.
One exception was Penzance where I spent my last five years happily flying to the Scillies. Into Scillies it was a Decca approach backed up by the NDB at St Mary's. Into Penzance it was quite the most complicated approach I've ever seen. It started with a VOR/DME fix and was carried out following a Decca track on the moving map with the final leg flown heights against distance to run. To be valid it required VOR and DME cross-checks at all salient points, final track checked against the NDB at PZ heliport, the rad alt and finally, Penzance swimming pool, very prominent on the Mounts Bay coast, had to be identified on the ac radar. Six of those in a morning at each end and you knew all about it.
What we wouldn't have given for an FMC (had we known they existed)
The beer and fishing, I have to admit, is fun, reward for a virtuous life I always say, but it would be nice to see how its done today.