It’s not common, but he does have a couple of stock patterns where he does it. Here’s one of the patterns, when you have two notes on a higher string and you try to cycle it with one note on a lower string. You can sweep the first string change but not the second one:
The reverse is also fairly uncommon, where you have descending inside alternate picking embedded in a phrase. So the bit in the here where you have 354, where 4 is a downstroke, and then you have to hit the 5 on an upstroke. That’s very uncommon in Frank’s playing.
In other words, when you have an economy type line that’s moving in a continuous direction, and you have a mix of inside picking and sweeping, you really don’t see much of that in Frank’s playing, even though in theory it should be common. If you look at George Benson for example, he’ll do DDU on two strings, like the A and D strings, then DDU again on the next pair of strings, like the G and B. Obviously the connection between them is inside picking but it’s no problem because it’s still one-way economy. Lots of jazz type lines work this way because of all the 212 type fingerings. I really had to look around and I wasn’t really able to find any examples of these kinds of lines in the interview.
The closest would be something like this:
Measure 7 has the first pattern we’re talking about, and measure 18 has it again with a transition to two notes per string, which is inside picking. It’s not quite the same thing as doing a 212 type line, but it’s sort of in the ballpark.