The problem with having thousands of hours 4-eng flights over several decades is that if you work for a bottom shelf airline or is not to sharp yourself, your knowledge tends to be several decades outdated, too.
For the last 10 years or so - since the LROPS requirements came - any 4-eng ops must be planned to allow a sudden
dual engine failure, driftdown, cruise and landing (conditions apply).
While this requirement is not limiting in most parts of the world, there are areas - including North-of-the-Big-Stones, where planning can be a bit tricky - unless of course you fly the fail-proof 747 and disregard or dont know current regulations..
3- and 4-engine have the same decompression challenges as 4-engine aircraft, hence the new FAA ETOPS regulations ( now also valid for quads). That is the reason pax aircraft flying in this part of the world, notably on AWY L999, carry enhanced oxygen systems. The standard 15 or 22 minutes versions will empty before reaching over low terrain, and you will have to plan carefully with escape routes.
Noblues, the generic escape routes must be adjusted for your actual situation (aircraft, oxygen, descent profile etc), but your question is absolutely relevant, so dont be put off by an ignorant, who retired (or should) decades ago.
