Has anyone not done CC with 1sr DC but gone into with the second?

[namechangerooey]

I thought DC1 was a bad sleeper but now realised she wasn't actually that bad!
DC2 sleeps terribly, I have no evenings and v little freedom as she is EBF too.
We left DC1 to grizzle a fair amount as she got older but never did any formal training. She didn't sleep through until 18 months and has been up and down since. Fairly okay now at 3 but can still play up sometimes.
I'm considering controlled crying in a couple of months if things don't improve with the gentler things I'm trying. Has anyone sleep trained their second but not their first and did the second end up a better sleeper?? I really don't want to put her through it if it'll make no difference anyway!

I did cc with ds2 when he was 13m as he was TERRIBLE! it did improve things for a while but now at 2.5 we seem to have gone backwards and having terrible sleep again so contemplating sleep training again! Never did any sleep training with ds1 as never really felt we needed too but ds2 is a different kettle of fish!