Compare the speed at which best Ld occurs. Also compare the Ld curve.
Some drop off faster than others. A steeper curve vs a flat curve.
A flat curve would maintain a higher Ld at faster speeds.

I fly an LS-4 cross country, best Ld is about 41, but at XC speeds of about 70kias, Ld is in lower 30s.

XC skills and ability to stay up in weak conditions improve with experience.
Practice, Practice, Practice.

I know pilots that go XC in SGS 1-26s, (23-1), Libelle (36-1), Grob 104 (41-1) and Janus C (2 seat 42-1)

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