I’m seeing different long-run behavior from two Illustrator ExtendScript patterns:

A)
var g = app.activeDocument.groupItems.add();
g.pathItems.rectangle(0, 0, 50, 50);

B)
var g = app.activeDocument.groupItems.add();
var r = app.activeDocument.pathItems.rectangle(0, 0, 50, 50);
r.move(g, ElementPlacement.PLACEATBEGINNING);

After each run I print:
$.writeln("Document: " + $.summary("Document"));
$.writeln("GroupItem: " + $.summary("GroupItem"));

Both should be similar logically, but Pattern A shows faster growth in $.summary("GroupItem"), while Pattern B seems more stable in repeated runs. Sometimes I eventually get:
An Illustrator error occurred: 1346458189 ('PARM').

Is this expected DOM-wrapper behavior? Is $.summary("GroupItem") reliable for script-engine pressure, or misleading?