Scripts are necessary to build some essential buildings. But the advantage they really provide is level 10 barracks to build catapults. But it takes a lot of scripts and you have to try to get a few every week.
Try to hit as soon as you can after server maintenance It seems 2 can drop in a few hits just after. This seems to be a regular occurrence and then you may or may not pick up a few later that day. If you ballista multi farm you can pick up 5 and over a day, but then again its not guaranteed. If you warrior farm you can pick up a massive amount.
So far the most I have picked up in a day is 17 Michelangelo scripts. This was from about 1600 attacks over a 12 hour period using archer rainbow / warrior farming.
Scripts are quite easy to farm. It does seem like they don't drop very often, but they actually do. If you use the right farming methods you can pick up on average 2 a day. But depending how often you farm you can increase this number significantly. So on average that's 14 a week, lets say. That's enough to get a good chunk of you barracks in one city scripted. If you get lucky with the drops a few days in a row you can get enough scripts for all your barracks, and maybe a few others building in 1 city in a few days. You need to use them properly and don't go wasting them on resource fields first and in cities that you will abandon later. Obviously if you take control of a Lv 14 Historic City or above, start scripting right away.