diff --git a/Documentation/technical/paint-down-to-common.adoc b/Documentation/technical/paint-down-to-common.adoc
index 2393bb03b6..c33c7ea7c1 100644
--- a/Documentation/technical/paint-down-to-common.adoc
+++ b/Documentation/technical/paint-down-to-common.adoc
@@ -148,43 +148,6 @@ candidate (generation ordering guarantees children are visited
 first), so it cannot be redundant and the walk can stop
 immediately.
 
-This optimization is NOT safe when the date-ordering fallback is
-active, because commit-date order can visit a deeper ancestor
-before a shallower one -- see <<date-ordering-fallback>>.
-
-[[date-ordering-fallback]]
-Date-ordering fallback
-----------------------
-
-When the commit-graph has generation numbers v1 and no
-generation floor is specified, topological ordering
-(via generation numbers) is disabled. Topological levels are
-correct but unbalanced -- ordering by such generation numbers
-can sometimes cause the walk to detour too far before finding
-merge bases. Commit-date ordering typically reaches them in
-fewer steps -- see this change for more details:
-
-   091f4cf3 (commit: don't use generation numbers if not needed,
-   2018-08-30)
-
-With generation number v2 (corrected commit dates) we have the best
-of both worlds and do not need this fallback.
-
-For v1, `paint_down_to_common()` falls back to pure commit-date
-ordering via `compare_commits_by_commit_date`. Because commit
-dates are not monotonic (clock skew, rebases, etc.), the queue
-may visit commits out of topological order.
-
-This disables the optimizations that depend on generation ordering:
-
-  - *Single result*: the first merge-base candidate found may not
-    be the shallowest, because a deeper ancestor with a higher
-    commit date can be dequeued first.
-
-  - *Side exhaustion*: one paint side can appear to drain from the
-    queue while commits from that side are still waiting with lower
-    dates, causing premature termination.
-
 Related documentation
 ---------------------
 
diff --git a/commit-reach.c b/commit-reach.c
index 7b9e21a8fc..2e50e81c54 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -89,7 +89,6 @@ struct paint_state {
 	size_t parent1_count;
 	size_t parent2_count;
 	size_t mb_candidate_count;
-	int gen_ordered;
 	timestamp_t min_generation;
 	timestamp_t last_gen;
 	timestamp_t topo_ceiling;
@@ -172,7 +171,6 @@ static struct commit *paint_queue_get(struct paint_state *state)
 
 		/* one side is exhausted */
 		if ((!state->parent1_count || !state->parent2_count) &&
-		    state->gen_ordered &&
 		    generation < state->topo_ceiling)
 			return NULL;
 	}
@@ -193,9 +191,13 @@ static int paint_down_to_common(struct repository *r,
 				enum merge_base_flags mb_flags,
 				struct commit_list **result)
 {
+	/*
+	 * Generation ordering is required for the side-exhaustion and
+	 * single-result early exits, which rely on topological traversal
+	 * order (children visited before parents) in the ordered region.
+	 */
 	struct paint_state state = {
-		.queue = { compare_commits_by_gen_then_commit_date },
-		.gen_ordered = 1,
+		.queue = { compare_commits_by_gen_then_commit_date }
 	};
 	struct commit *commit;
 	int i;
@@ -207,10 +209,6 @@ static int paint_down_to_common(struct repository *r,
 	state.topo_ceiling = corrected_commit_dates_enabled(r)
 		? GENERATION_NUMBER_INFINITY
 		: GENERATION_NUMBER_V1_MAX;
-	if (!min_generation && !corrected_commit_dates_enabled(r)) {
-		state.queue.compare = compare_commits_by_commit_date;
-		state.gen_ordered = 0;
-	}
 
 	one->object.flags |= PARENT1;
 	if (!n) {
@@ -238,7 +236,6 @@ static int paint_down_to_common(struct repository *r,
 				 * descendant of this one.
 				 */
 				if (!(mb_flags & MERGE_BASE_FIND_ALL) &&
-				    state.gen_ordered &&
 				    state.last_gen < state.topo_ceiling)
 					break;
 			}
diff --git a/t/t6600-test-reach.sh b/t/t6600-test-reach.sh
index 4373fee521..b933b6f55a 100755
--- a/t/t6600-test-reach.sh
+++ b/t/t6600-test-reach.sh
@@ -381,7 +381,7 @@ test_expect_success 'get_merge_bases_many:infinity-both-sides' '
 		git rev-parse pi-B
 	} >expect &&
 	test_all_modes get_merge_bases_many &&
-	test_paint_down_steps 5 4 5 5
+	test_paint_down_steps 5 4 5 4
 '
 
 test_expect_success 'setup mixed finite/INFINITY topology' '
@@ -414,7 +414,7 @@ test_expect_success 'merge-base --all commit-walk steps' '
 	>input &&
 	git rev-parse commit-9-1 >expect &&
 	run_all_modes git merge-base --all commit-9-9 commit-9-1 &&
-	test_paint_down_steps 81 9 57 81
+	test_paint_down_steps 81 9 57 37
 '
 
 test_expect_success 'merge-base --all with clock skew (side-exhaustion)' '
@@ -423,7 +423,7 @@ test_expect_success 'merge-base --all with clock skew (side-exhaustion)' '
 	>input &&
 	git rev-parse se-D >expect &&
 	run_all_modes git merge-base --all se-A se-B &&
-	test_paint_down_steps 6 4 6 6
+	test_paint_down_steps 6 4 6 4
 '
 
 test_expect_success 'merge-base --all with clock skew and redundant ancestor (side-exhaustion)' '
@@ -433,7 +433,7 @@ test_expect_success 'merge-base --all with clock skew and redundant ancestor (si
 	>input &&
 	git rev-parse se2-MB1 >expect &&
 	run_all_modes git merge-base --all se2-A se2-B &&
-	test_paint_down_steps 8 6 8 8
+	test_paint_down_steps 8 6 8 6
 '
 
 test_expect_success 'reduce_heads' '