While you could technically use bottled, I find that fresh lemon juice really makes all the difference!
I find this drink fairly well balanced in both sweetness and strength as written, but you can of course tailor to your preferences by adjusting the amount of vodka and the amount of simple syrup
One medium lemon usually gives about 1 ½ – 2 ounces of juice in total, for help if you plan to scale the recipe! Of course, this can vary slightly between fruits, so I usually pick up a couple extra