Even one-time pads are subject to the efforts used to counter Enigma, such as so-called gardening. I fully agree that layers are better than a single method like Enigma was many times in practice, which is usually all-or-none with no failsafe, at least until later in the war, when Enigma variants started being used in combination with coded messages and code words on top of the Enigma cipher machines themselves, but those efforts were foiled by the dedication and planning of the gardeners’ known-plaintext attacks.
https://en.wikipedia.org/wiki/Gardening_(cryptanalysis)
> In cryptanalysis, gardening is the act of encouraging a target to use known plaintext in an encrypted message, typically by performing some action the target is sure to report. It was a term used during World War II at the British Government Code and Cypher School at Bletchley Park, England, for schemes to entice the Germans to include particular words, which the British called "cribs", in their encrypted messages. This term presumably came from RAF minelaying missions, or "gardening" sorties. "Gardening" was standard RAF slang for sowing mines in rivers, ports and oceans from low heights, possibly because each sea area around the European coasts was given a code-name of flowers or vegetables.
> The technique is claimed to have been most effective against messages produced by the German Navy's Enigma machines. If the Germans had recently swept a particular area for mines, and analysts at Bletchley Park were in need of some cribs, they might (and apparently did on several occasions) request that the area be mined again. This would hopefully evoke encrypted messages from the local command mentioning Minen (German for mines), the location, and perhaps messages also from the headquarters with minesweeping ships to assign to that location, mentioning the same. It worked often enough to try several times.