Tom Clancy's The Division, which is not really Tom Clancy's but never mind, is heading for another Global Event day after tomorrow, 24 September 2018, and considering Ambush's buffs, it may be smart to have a go at Survival while it lasts.
As you're probably well aware by now, Ambush rewards staying stationary and/or in cover, which grants you a damage buff that you can see above your health bar. As long as you stick to not moving, your bar increases, while movement triggers it to go the other way around.
Activating Covert Ambush means that you'll be paying for movement in health once your Ambush bar hits zero, while Strategic Ambush does the same when close to allies. I guess friends don't always make you stronger, do they Jerry? Don't mind me, moving on.
What this means in practice, or in the field if you will, is that if you needed help to get flawless on legendary missions, look no further than Ambush. More importantly though, completing Survival is probably best done this week and if you've actually tried it, you probably already know that this is the case.
Thankfully, Ambush's buffs will come in handy, because even the bog standard pistol you start off with lets you wreak serious havoc. Needless to say, any turret assistance you can muster, regardless of how useless it may seem in regular play, will make a world of difference in Survival. So yeah - it's pretty wise to do it while Ambush is ongoing.
Note that if you're actually using cover to cover movement (space bar on PC, A on Xbox One), your Ambush buff will not be decreasing, which is quite likely the best tip one could give. If you run from cover to cover though, you'll be sacrificing damage so it's a no brainer really.
Unfortunately for cheap-skaters of the world, Massive and Ubisoft won't be humouring us with more free weekends, at least this month. We did however find out about four months of The Division's Global Events thanks to data miners and you can check them out here.