From what I have seen, a person can achieve GMAT score increases as long as she or he keeps going, uses effective approaches, and keeps finding new levers to pull.
We often hear that people's GMAT scores top out at certain levels, but to understand what's going on, we have to examine those stories thoroughly and ask ourselves whether those people kept going, used effective approaches, and kept finding new levers to pull.
Many people believe in score ceilings or don't really care to achieve large score increases. So, simply looking at what happened without considering why it happened is not particularly useful. Sure, someone achieved a score increase of under 100 points and didn't achieve any increase from her or his second to third GMAT, but what did that person do, or not do, when preparing?
On a related note, the current GMAT Club score increase record, and what is quite possibly the largest GMAT score increase ever, was achieved by member
daldilaimi, who achieved a
530 point score increase, going from her first GMAT score of 250 to her final GMAT score of 780.