how does ἔστιν ὅτε function in this segment from Thucydides

[Laertiades]

I´m struggling with how ἔστιν ὅτε is functioning in this passage from Thucydides, Book 1 - chapter 25. If someone would be willing to provide some insight, I would be grateful. Thanks in advance for any help.

ναυτικῷ δὲ καὶ πολὺ προύχειν ἔστιν ὅτε ἐπαιρόμενοι καὶ κατὰ τὴν Φαιάκων προενοίκησιν τῆς Κερκύρας κλέος ἐχόντων τὰ περὶ τὰς ναῦς

Source: http://www.perseus.tufts.edu/hopper/tex ... ection%3D4

[Paul Derouda]

ἔστιν ὅτε is a fixed elliptical expression that means approximately "at times", "now and then"; in this particular case, it seems to mean "often". See LSJ ὅτε A.4.2. ὅτε doesn't connect closely with what follows like ὅτε usually does.