I have used that approach before with sentry. It was a non-issue. It depends on nature of the project of course, we had a system that was running every second so if it failed it generated a lot of data..
I agree. Sampling logs.. sounds dangerous. Obviously every system is different.
At least in GCP you can apply a filter to prevent ingestion and set different expiries on log budgets. This can help control costs without missing important entries.