Which counter exactly?

If you really do mean the 'log cache hit ratio' then that's got nothing to do with the buffer pool, nothing to do with optimise for ad-hoc usage and nothing to do with locked pages.

The log cache hit ratio is describes as

"Percentage of log cache reads that were satisfied from the log cache."

Now, reading from the transaction log is not a common activity, I would guess you have replication perhaps? It's also not something I'd expect to see hitting cache, you don't typically read the same log records multiple times.

To be honest, that's a counter I wouldn't even bother looking at, let alone worrying about.