I would like to encourage my bees to draw out foundation into the new frames ... by moving one or two into the centre come March/April.
I'm no expert, but from what I've read, the verdict would be: not good.
There are beekeeping methods that involve adding empty frames or foundation into the middle of the brood nest to encourage it to expand, but those procedures are done on strong, healthy, growing colonies. In other words, they promote additional growth after the growth spurt has begun.
If your colony is still small, and/or is not going through a growth spurt, then putting an empty frame or foundation in the middle of the nest will do nothing but make it harder for them to keep their temperature steady. Their priority will not magically become "comb building" just because there is a sudden gap in the centre of their nest.
If you want to expand a small colony such as yours, put the nest in the centre of the box (or against the side of the box, say some people), and add empty frames or foundation next to it.
Since your colony is in a nuc box (presumably), you don't need to add a follower board to make the nest cavity smaller, but if these bees were in a larger box, you'd find yourself advised to make the cavity more cozy by adding a snug fitting follower board, and only add one or two new frames at a time and wait until they are beginning to fill up before adding new ones.
If you place them against the side wall, adding foundation to the middle they will put all there energy on working in one direction instead of trying to work on two fronts, a good nuc will usually draw out all the foundation frames in a week.
I wonder if that isn't just appearance. I mean, if they draw out foundation at an equal pace regardless of whether they're working in one direction or two directions, then it would appear (to you, the outside observer) that they're working faster if they are able to go only in one direction, but they wouldn't actually be working any faster or better on the whole. Right?
What would you say to the argument that working in two directions would reduce them stepping on each others toes (so to speak) in their frenzy to build new comb?
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