You’re partially right. It’s a widget on xivanalysis that highlights weaving issues. E.g. late ogcd weaves or extra ogcd weaves clipping into your gcds and costing you gcd uptime (“always be casting,” “keep your gcds rolling”).

Low number of weaves with high time between gcds means they’re standing around. High number of weaves between gcds means they are spamming ogcds and not using gcds - so not necessarily standing around, but very suboptimal and probably with a significant cost to dps.

Depending on class and build, they probably don’t want more than 2.3-2.5 seconds between gcds. And you generally can’t weave more than 1-2 ogcds without clipping into your gcds.