An LE cert can have up to 100 entries.
So, you could combine many "levels" into one cert.
Like:
*.example.com
*.sub1.example.com
*.sub2.example.com
*.sub3.example.com
*.sub4.example.com
*.sub1.extra1.example.com
*.sub2.extra1.example.com
*.sub3.extra1.example.com
*.sub4.extra1.example.com
*.sub1.extra2.example.com
*.sub2.extra2.example.com
*.sub3.extra2.example.com
*.sub4.extra2.example.com
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