[boomlinde]

> Coincidentally there are no commonly used scales or modes with two consecutive semitones.

It's common in Bebop to add a passing tone to otherwise heptatonic scales. Consecutive semitones are also a common feature in blues.

[xavriley]

That’s true but in those cases they are passing tones. For examples in a bebop scale you don’t tend to arpeggiate using both the consecutive tones.

[boomlinde]

> That’s true but in those cases they are passing tones.

That may well be their main function, especially in bebop (it's not so certain in blues), but they're still considered as part of the scale.

> For examples in a bebop scale you don’t tend to arpeggiate using both the consecutive tones.

That's true for any non-chord tones. The intervals are still very common (in bebop you commonly simply walk the whole scale up and/or down in straight 8ths or 16ths, playing adding the passing tone for the chord tones to end up on the downbeats).