diff --git a/src/libraries/DrawAccumulatorLib.sol b/src/libraries/DrawAccumulatorLib.sol
index 4f8ef4c..da8d27c 100644
--- a/src/libraries/DrawAccumulatorLib.sol
+++ b/src/libraries/DrawAccumulatorLib.sol
@@ -46,12 +46,6 @@ library DrawAccumulatorLib {
     mapping(uint256 drawId => Observation observation) observations;
   }
 
-  /// @notice A pair of uint24s.
-  struct Pair48 {
-    uint24 first;
-    uint24 second;
-  }
-
   /// @notice Adds balance for the given draw id to the accumulator.
   /// @param accumulator The accumulator to add to
   /// @param _amount The amount of balance to add
@@ -103,10 +97,7 @@ library DrawAccumulatorLib {
 
       return true;
     } else {
-      accumulatorObservations[newestDrawId_] = Observation({
-        available: SafeCast.toUint96(newestObservation_.available + _amount),
-        disbursed: newestObservation_.disbursed
-      });
+      accumulatorObservations[newestDrawId_].available = SafeCast.toUint96(newestObservation_.available + _amount);
 
       return false;
     }
@@ -161,56 +152,48 @@ library DrawAccumulatorLib {
       return 0;
     }
 
-    uint24 firstObservationDrawIdOccurringAtOrAfterStart;
-    if (_startDrawId <= oldestDrawId || ringBufferInfo.cardinality == 1) {
-      firstObservationDrawIdOccurringAtOrAfterStart = oldestDrawId;
-    } else {
-      // The start must be between newest and oldest
-      uint24 beforeOrAtDrawId;
-      // binary search
-      (
-        ,
-        beforeOrAtDrawId,
-        ,
-        firstObservationDrawIdOccurringAtOrAfterStart
-      ) = binarySearch(
-        _accumulator.drawRingBuffer,
-        uint16(oldestIndex),
-        uint16(newestIndex),
-        ringBufferInfo.cardinality,
-        _startDrawId
-      );
-      if (beforeOrAtDrawId == _startDrawId) {
-        firstObservationDrawIdOccurringAtOrAfterStart = _startDrawId;
+    // check if the start draw has an observation, otherwise search for the earliest observation after
+    Observation memory atOrAfterStart = _accumulator.observations[_startDrawId];
+    if (atOrAfterStart.available == 0 && atOrAfterStart.disbursed == 0) {
+      if (_startDrawId <= oldestDrawId || ringBufferInfo.cardinality == 1) {
+        atOrAfterStart = _accumulator.observations[oldestDrawId];
+      } else {
+        (, uint24 beforeOrAtDrawId, , uint24 afterOrAtDrawId) = binarySearch(
+          _accumulator.drawRingBuffer,
+          oldestIndex,
+          newestIndex,
+          ringBufferInfo.cardinality,
+          _startDrawId
+        );
+        if (beforeOrAtDrawId == _startDrawId) {
+          atOrAfterStart = _accumulator.observations[_startDrawId];
+        } else {
+          atOrAfterStart = _accumulator.observations[afterOrAtDrawId];
+        }
       }
     }
 
-    uint24 lastObservationDrawIdOccurringAtOrBeforeEnd;
-    if (_endDrawId >= newestDrawId || ringBufferInfo.cardinality == 1) {
-      // then it must be the end
-      lastObservationDrawIdOccurringAtOrBeforeEnd = newestDrawId;
-    } else {
-      uint24 afterOrAtDrawId;
-      (, lastObservationDrawIdOccurringAtOrBeforeEnd, ,afterOrAtDrawId) = binarySearch(
-        _accumulator.drawRingBuffer,
-        uint16(oldestIndex),
-        uint16(newestIndex),
-        ringBufferInfo.cardinality,
-        _endDrawId
-      );
-      if (afterOrAtDrawId == _endDrawId) {
-        lastObservationDrawIdOccurringAtOrBeforeEnd = _endDrawId;
+    // check if the end draw has an observation, otherwise search for the latest observation before
+    Observation memory atOrBeforeEnd = _accumulator.observations[_endDrawId];
+    if (atOrBeforeEnd.available == 0 && atOrBeforeEnd.disbursed == 0) {
+      if (_endDrawId >= newestDrawId || ringBufferInfo.cardinality == 1) {
+        atOrBeforeEnd = _accumulator.observations[newestDrawId];
+      } else {
+        (, uint24 beforeOrAtDrawId, , uint24 afterOrAtDrawId) = binarySearch(
+          _accumulator.drawRingBuffer,
+          oldestIndex,
+          newestIndex,
+          ringBufferInfo.cardinality,
+          _endDrawId
+        );
+        if (afterOrAtDrawId == _endDrawId) {
+          atOrBeforeEnd = _accumulator.observations[_endDrawId];
+        } else {
+          atOrBeforeEnd = _accumulator.observations[beforeOrAtDrawId];
+        }
       }
     }
 
-    Observation memory atOrAfterStart = _accumulator.observations[
-      firstObservationDrawIdOccurringAtOrAfterStart
-    ];
-
-    Observation memory atOrBeforeEnd = _accumulator.observations[
-      lastObservationDrawIdOccurringAtOrBeforeEnd
-    ];
-
     return atOrBeforeEnd.available + atOrBeforeEnd.disbursed - atOrAfterStart.disbursed;
   }