Alert: if you do GC on ArGIS Online you get warning messages if your job get big, meaning uses lots credits. If you open a large # of vertices in ArcGIS Desktop you also get an alert if the # vertices exceeds 2500. But if you do GC on Desktop using AGOL option, you get no warning if the job gets huge: I ate up 3000+ credits before it failed... and I'm not sure if the error was credit or otherwise related! Local distro told me another customer exceeded 20K, so I guess I got off lightly. Note to Esri, please address this ASAP.