Any route with a roughly 10 hour flight time each way is a candidate for using the same aircraft day in, day out.

Elsewhere, sweating the assets means an endless merry-go-round of different aircraft on any one route. I once noted the registration of a BA 747 taxying out at Hong Kong as I waited to board the CX 888 for New York via Vancouver. When I finally arrived at JFK, the exact same aircraft was there too - it had semi-circumnavigated the globe in the other direction, via London.