Well to give you a live example.
Back in 2006, my sister gave her 10th Board exams. She left a six marks question in her Social Science paper. Her score was 96%.
Coming to Class 12th. In 2015, the physics exam was tough. I had lost hopes as my expected score was merely crossing 50.
I ended up scoring 61/70 in Physics.
Board checking can’t be lenient or tough but it can surprise you to unknown extents.
Leave the worries and study for other exams.
Keep up voting.
All the best!