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[Silfir]

Not really. Overwatches were mostly, except under certain circumstances and with certain specific character builds, a sucker's bet and trap. Particularly in higher levels of difficulties, moving to partial cover and going into overwatch is absolutely a BAD idea compared to making a sprint to full cover and no overwatch. The overwatch penalty alone is effectively giving enemies at a minimum partial cover. This gets exasperated under conditions such as distance penalties (because overwatch triggers the moment it is possible, not when it is optimal), already existing cover when overwatch triggers, and other factors. In many cases, you actually have a BETTER shot had you NOT gone into overwatch, but simply Hunkered to deny an enemy a good shot at you, then fired in response.

The primary example when overwatch is appropriate is a) Longwatch Sniper, because his job, when not directly plugging aliens, is to find a good sniper's roost that has a commanding view over the majority of where the team is moving and respond in the event a pack either 'self activates' by patrolling movements or someone activates a pack prematurely, or b) someone with the ability to apply a useful effect even if they miss, such as when the soldier has the perk that gives an aim bonus to subsequent shooters at that target.

The overwatch crawl is a 'newbie tactic', and very rarely optimal in nearly any circumstance. It often places the soldiers in greater danger than moving without insisting on being on overwatch every turn due to availability of full cover vs partial cover and 'discovered packs', and survivability.

I'm almost certain you're talking about something else entirely. No one's suggesting Overwatch is a good idea if you've activated any pods and are engaged in combat; it's what you do while no pods are active that's the issue. The optimal strategy, sans timer, is a slow crawl across the map, hoping to catch the aliens patrolling... unless the mission happens to have a turn limit.