Mine looks something like this…I only left one Level 3 index in here to keep the size reasonable (and avoid potential embarrasment)
00-09 Meta
00-09 Meta /00 Index
00-09 Meta /01 Zettelkasten
00-09 Meta /02 Journal
00-09 Meta /02 Journal/2021
00-09 Meta /03 Tasks
00-09 Meta /03 Tasks/03.01 Need To Sort
10-19 Hobbies
10-19 Hobbies/11 Birding
10-19 Hobbies/12
10-19 Hobbies/13 Learning
10-19 Hobbies/14 Music
10-19 Hobbies/15 Recipes
10-19 Hobbies/16 Travel
20-29 Maintenance
20-29 Maintenance/21 Fitness
20-29 Maintenance/22 Manuals
20-29 Maintenance/23 Vehicles
30-39 Finance
30-39 Finance/31 Insurance
30-39 Finance/32 Investing
30-39 Finance/33 Misc
30-39 Finance/34 Receipts
30-39 Finance/35 Retirement
30-39 Finance/36 Schwab
30-39 Finance/37 Taxes
30-39 Finance/38 Titles and Deeds
40-49 Miscellaneous
50-59 Genealogy
50-59 Genealogy/51 Dixon
50-59 Genealogy/51 Dixon/51.01 Bible Records
50-59 Genealogy/51 Dixon/51.02 Birth Records
50-59 Genealogy/51 Dixon/51.03 Cemeteries
50-59 Genealogy/51 Dixon/51.04 Census Records
50-59 Genealogy/51 Dixon/51.05 Correspondence
50-59 Genealogy/51 Dixon/51.06 DNA Records
50-59 Genealogy/51 Dixon/51.07 Death Records
50-59 Genealogy/51 Dixon/51.08 Descendant Files
50-59 Genealogy/51 Dixon/51.09 GEDCOM files
50-59 Genealogy/51 Dixon/51.10 Genealogical Societies
50-59 Genealogy/51 Dixon/51.11 HTML Export
50-59 Genealogy/51 Dixon/51.12 Heredis
50-59 Genealogy/51 Dixon/51.13 Histories
50-59 Genealogy/51 Dixon/51.14 Houses
50-59 Genealogy/51 Dixon/51.15 Maps
50-59 Genealogy/51 Dixon/51.16 Marriage Records
50-59 Genealogy/51 Dixon/51.17 Military Records
50-59 Genealogy/51 Dixon/51.18 Mills
50-59 Genealogy/51 Dixon/51.19 Miscellaneous
50-59 Genealogy/51 Dixon/51.20 PDFs to Extract
50-59 Genealogy/51 Dixon/51.21 Pedigree Files
50-59 Genealogy/51 Dixon/51.22 Photos
50-59 Genealogy/51 Dixon/51.23 Quaker Records
50-59 Genealogy/51 Dixon/51.24 Research
50-59 Genealogy/51 Dixon/51.25 School Records
50-59 Genealogy/51 Dixon/51.26 TheDixons
50-59 Genealogy/51 Dixon/51.27 Transport Records
50-59 Genealogy/51 Dixon/51.28 UK
50-59 Genealogy/52 Gilmore
50-59 Genealogy/53 Peterson
50-59 Genealogy/54 Rees
50-59 Genealogy/55 General
50-59 Genealogy/56 Heredis
60-69 Writing
60-69 Writing/61 Books-Essays
60-69 Writing/62 General
60-69 Writing/63 Miscellaneous
60-69 Writing/64 Multimedia
60-69 Writing/65 Non-fiction
60-69 Writing/66 Web Sites