No, LAG isn't optimal for SnG's at all. The blinds go up too quickly basically. All sng's are going to degrade to a match in which all decisions are if shoving is +EV, and then you're either shoving preflop or folding.
Playing LAGgy to accumulate chips works with long levels and small blind structure, because people have larger M's and are willing to cut loose from marginal hands, since they know they'll have a better spot.
In Sng's you're either playing small stakes, where there are lots of loose donks, or you're playing higher where people understand correct sng strategy. If the former is the case, lag breaks down since your fold equity disappears. In the latter, you're going to take blinds quite a bit, and if you get into a pot, you're probably going to be quite far behind, and end up bleeding off your stack when there's no real need.
Even doubling up early on does little to advance your position. It's not bad to do so, but all it really does is delay how long it takes before you personally have to switch to a shove/fold preflop strategy.