If you can cover it, do it cheaply. If you are in your room and you can see across you got too much light but its just going to SLOW your flowering not necessarily kill it. Think about the night time outside, most of the time there is heavy moonlight and I have seen some damn AAA outdoor gear roll. The point is to have them in complete darkness at night, dont flash the damn things with camera shots and bedroom lights, keep major light sources blacked out and just chill and grow.
Covering up light strip lights.. ehhh too each their own, the point being its your personal preference if you are having trouble with slow formation, weak bud, lower overall quality and all your environments and nutes are in check, look for leaks of major light. I like to just go by keep it simple stupid or KISS, if you are even talking about light leaks, then your probably a hobby grower and you should not really worry about it. ;-)