Sentinel for small targets

This is a basic question. I’ve read about InSAR, Sentinel and its applications, for example, to determine the deformation rate in volcanic regions. But I see that on small volcanic islands, such as Stromboli in Italy (with a “diameter” of ~4.5km), InSAR is not widely used. Why? What is the relationship between the size of a “target” and the capability of a sensor like Sentinel? What is the decisive factor for the application of InSAR analysis to small targets (like a small island)?

Rather than the size of an area, what really limits the chances for successful applications of DInSAR is the lack of open surfaces. If a small island consists of forest only, there will be no stable phase information.
Maybe that is part of the reasons why there are fewer studies on isolated areas of limited size.
Even persistent scattererer approaches which are less prone to phase decorrelation struggle with small islands, if you take my study as an example: