Hey Akueck,
I stir for about about two minutes or so each time up to the 1/2 sugar break. I don't play any hard and fast rules though because each batch is different so I treat each of them differently. I start on very slow speed and get the must moving, and then bring the lees stirrer to the top of the must and out of it to let the paddles swat the top of the must and agitate it well, and then back down. Mind you this is all done on a very slow speed. Do it fast and you'll have a volcano the likes of which only the Diet Coke/Mentos guys would appreciate!
That doesn't mean I have wild variations for each batch, but it does mean that I actually pay attention to the progress of the fermentation in each vessel, and treat them all by batch rather than as total collective.
What I mean by that is if I make a thirty gallon batch of traditional sweet mead, I treat the five carboys pretty much the same with regard to racking, stirring, dosing, aerating, etc. However, if I started a 30 gallon batch of cyser at the same time, I'll follow a different schedule so I'm able to manage it as a cyser rather than as a traditional.
There are also times when I will treat each carboy from a larger batch as an individual, especially when oaking or other treatments. It really boils down to you as the Meadmaker making a judgement call based on what you want as an end product. That's the tough thing about making a large batch of mead, and then having it ferment and age in smaller containers. Meadmaking to me is a very long series of decision points from purchase of the honey, to bottling.
What is the exact cyser recipe, and which yeast did you use? That will help to figure out what you're looking at as far as what kind of stirring you need to do.
The solid top is on the bottle and set in place only, it is not twisted down so it literally just sits there to keep stuff out while I take photos and such. My cloth covering was looking gnarley so I decided to go with something a bit more pleasing to the eye. I also run some fermentations with a cap like you see in the photo in place, but not screwed down. I've never had one blow off though. Some barrel fermentations I've seen in France use a drilled bung with a stanless steel bolt dropped through the hole, when the pressure builds up enough it lifts the bolt a little and the pressure disperses. Mind you this was in a barrel fermented Chablis (Pinot Chardonnay grape), but the wine was superlative!
Cheers,
Oskaar