The percentage of checkpoint sync time spent in reconciliation across all threads has a ceiling of thread count times 100, so it cannot be interpreted without knowing how many checkpoint reconciliation threads are configured. WiredTiger has no stat for that count, only the checkpoint_threads open config and a debug-level verbose line, which is why HELP-100496 stalled on a 375 reading. Add a CheckpointStat gauge set from WT_PARALLEL_CHECKPOINTS_NUM_THREADS, mirroring how eviction already publishes eviction_active_workers.