I was listening to the latest episode of The History of English podcast and the host talked about rules for when final letters are doubled in English. One of the things he said was that if a consonant is doubled at the end of a word, it’s probably S, L, F, or Z.
I tested this empirically and found the following stats. The numbers basically confirm what the host said.
The “double” column counts double letters at the end of a word, and the “all” column counts all words ending in the given letter, single or double.
|---+--------+-------+----|
| | double | all | % |
|---+--------+-------+----|
| b | 8 | 476 | 2 |
| c | 0 | 11324 | 0 |
| d | 18 | 15996 | 0 |
| f | 218 | 919 | 24 |
| g | 11 | 6432 | 0 |
| h | 1 | 4754 | 0 |
| j | 0 | 17 | 0 |
| k | 1 | 2650 | 0 |
| l | 740 | 14929 | 5 |
| m | 2 | 8881 | 0 |
| n | 31 | 19966 | 0 |
| p | 10 | 2201 | 0 |
| q | 0 | 6 | 0 |
| r | 35 | 15467 | 0 |
| s | 9559 | 26062 | 37 |
| t | 51 | 14831 | 0 |
| v | 0 | 37 | 0 |
| w | 0 | 702 | 0 |
| x | 0 | 793 | 0 |
| y | 0 | 27747 | 0 |
| z | 22 | 143 | 15 |
|---+--------+-------+----|
These stats simply count words; I suspect the results would be different if the words were weighted by frequency. For example, there are eight words that end in bb, but seven of these are rare words or alternate spellings: abb, bibb, dabb, dhabb, dubb, ebb, hubb, stubb.