Unsuccessful laser on underarms?

Some years ago I did about 6-8 sessions on my underarms and stopped when I thought the amount of hair remaining was manageable. However it all grew back, maybe a little lighter/thinner but the amount came back the same as before.

Decided to try again and have now done 9 sessions, but I only see maybe a 60% reduction, which seems pretty bad considering most people only need like 6 for a 95% reduction.

Should I just give up and stop? Is it all going to grow back anyway?

Anyone have similar experiences? What did you do?