Is it very important?
For me it helped a lot. Thanks to timed practice, i finished both sctions with spare time back in dec 2012, so i had time to check my unsure or unfilled answers.
I felt more exhausted when doing L1 than L2. It was because non-stop thinking, punching calculator and filling the bubbles.
L1 you have 120 questions each sections. If you dont practice speed, there’s good chance you will run out of time ( like i did in level 2 in June. i didnt do any timed mocks for L2 as my end-may leave was cancelled).
I did schweser/elan/cfai mocks for L1 . Many of them were timed. It helped a lot
During the last month, invaluable. You want to simulate real exam conditions as closely as you can.