diff --git a/app/scodoc/sco_preferences.py b/app/scodoc/sco_preferences.py
index 4131e7f7..5037a31d 100644
--- a/app/scodoc/sco_preferences.py
+++ b/app/scodoc/sco_preferences.py
@@ -610,6 +610,17 @@ class BasePreferences(object):
                     "category": "assi",
                 },
             ),
+            (
+                "periode_defaut",
+                {
+                    "initvalue": 2.0,
+                    "size": 10,
+                    "title": "Durée par défaut d'un créneau",
+                    "type": "float",
+                    "category": "assi",
+                    "only_global": True,
+                },
+            ),
             (
                 "etat_defaut",
                 {
diff --git a/app/static/js/assiduites.js b/app/static/js/assiduites.js
index bf3d821b..3848af83 100644
--- a/app/static/js/assiduites.js
+++ b/app/static/js/assiduites.js
@@ -1263,7 +1263,9 @@ function actualizeEtud(etudid) {
  */
 function generateAllEtudRow() {
   if (isSingleEtud()) {
-    actualizeEtud(etudid);
+    try {
+      actualizeEtud(etudid);
+    } catch (ignored) {}
     return;
   }
 
diff --git a/app/templates/assiduites/timeline.j2 b/app/templates/assiduites/timeline.j2
index b67fd0b6..590c83a5 100644
--- a/app/templates/assiduites/timeline.j2
+++ b/app/templates/assiduites/timeline.j2
@@ -9,8 +9,10 @@
 
     const timelineContainer = document.querySelector(".timeline-container");
     const periodTimeLine = document.querySelector(".period");
-    const t_start = {{ t_start }}
-    const t_end = {{ t_end }}
+    const t_start = {{ t_start }};
+    const t_end = {{ t_end }};
+
+    const period_default = {{ periode_defaut }};
 
     function createTicks() {
         let i = t_start
@@ -157,7 +159,7 @@
         const computedValues = [Math.max(startValue, t_start), Math.min(t_end, endValue)]
 
         if (computedValues[0] > t_end || computedValues[1] < t_start) {
-            return [8, 10]
+            return [t_start, min(t_end, t_start + period_default)]
         }
 
         if (computedValues[1] - computedValues[0] <= 0.25 && computedValues[1] < t_end - 0.25) {
@@ -168,6 +170,8 @@
     }
 
     function setPeriodValues(deb, fin) {
+        deb = snapToQuarter(deb)
+        fin = snapToQuarter(fin)
         let leftPercentage = (deb - t_start) / (t_end - t_start) * 100
         let widthPercentage = (fin - deb) / (t_end - t_start) * 100
         periodTimeLine.style.left = `${leftPercentage}%`
@@ -199,7 +203,7 @@
     }
 
     createTicks();
-    setPeriodValues(8, 9)
+    setPeriodValues(t_start, t_start + period_default)
 
 </script>
 <style>
diff --git a/app/views/assiduites.py b/app/views/assiduites.py
index 11326ac6..2ebb777b 100644
--- a/app/views/assiduites.py
+++ b/app/views/assiduites.py
@@ -444,9 +444,12 @@ def _module_selector(
     )
 
 
-def _timeline() -> HTMLElement:
+def _timeline(formsemestre_id=None) -> HTMLElement:
     return render_template(
         "assiduites/timeline.j2",
         t_start=get_time("assi_morning_time", "08:00:00"),
         t_end=get_time("assi_afternoon_time", "18:00:00"),
+        periode_defaut=sco_preferences.get_preference(
+            "periode_defaut", formsemestre_id
+        ),
     )