It's pretty tough to get the significant achievement points. The guidance notes state this:
7.4.3 Two scoring levels are available. Those who can show significant achievement may not be known outside their field of expertise, or not yet be recognised on an international basis but have developed a body of work that is acknowledged by their peers as contributing significantly to the development of their area of work. 7.4.4 Those with an exceptional achievement in their chosen field will be at the top of their profession, be recognised beyond their field of expertise and have obtained international recognition.
If you look at the examples for each type of achievement, it is beyond scholarships. If you had a scholarship, had an invention, won a nationally recognized prize, had press writeups about it, and had publications that were of note, then you'd probably get the points. To get the exceptional achievement points, they give the example of a Nobel Prize!

Somehow, I don't think anyone with a Nobel Prize would be applying for HSMP!

Any country that person wanted to go to, would allow them in -- any university or industry would gladly do all the immigration paperwork!
There's no reason not to try to get sig achievement if you have 3 things to document it. Why not? All they can do is not give you points. Of course, you can irritate the caseworker, but they seem so inconsistent these days, who knows what they are thinking anyway.
My hubby applied for sig achievement and we have no idea if they gave him the points (first app approved, but had to reapply again). He had three publications in prestigious journals that had been cited numerous times by the biggest people in his field and one top guy (academic ref) wrote that hubby had "changed the way we see the early universe."

He also had a glowing letter from a successful president of a company that was nearly embarrassing for hubby to read, it was so complimentary. We still didn't expect for my hubby to get the points. And unless you have to get sig achievement to get enough points to be approved or you get rejected, no one really knows if they were awarded those points anyway, since the HO doesn't give a point breakdown in the approval letter.