Google N-gram Corpus Counts
╭─ーーーーーー─┬─────────┬───────╮
│ 休み時間　　 │ 326,353 │ 98.0% │
│ 休みじかん　 │   2,070 │  0.6% │
│ やすみ時間　 │     641 │  0.2% │
│ 休時間　　　 │     385 │  0.1% │
│ やすみじかん │   3,574 │  1.1% │
╰─ーーーーーー─┴─────────┴───────╯

@@ -8,0 +9 @@
+<ke_inf>&sK;</ke_inf>

@@ -5,0 +6,3 @@
+</k_ele>
+<k_ele>
+<keb>やすみ時間</keb>

(a) no need for the note, as it's quite clear from the glosses.
(b) no need for a "lit" if the gloss works by itself.
See: http://www.edrdg.org/wiki/index.php/Editorial_policy#Meanings : ``Note that the "[lit]" tag should not be used for such things as literal translations of the kanji in a jukugo.''

@@ -12,1 +12,0 @@
-<s_inf>Primarily used for school breaks, especially short break between classes.</s_inf>
@@ -14,1 +13,1 @@
-<gloss g_type="lit">break time</gloss>
+<gloss>break time</gloss>

GG5, 英辞郎

Closest translation is “recess”, which has same educational connotations.
Also used for vacations (multi-day breaks) and intermissions (at a play), AFAICT.