Bay Laural Hedge

Hi
I planted 2m high bay laurals into a raised planter above the patio and want to create a solid hedge (photo attached)

The raised planter is c. 30 cm wide and 40 cm deep and is open to the soil below. The soil is clay (as far as i can tell) and i put come fish blood and bone in when planting and mulched with manure. I'm watering it every few days but its holding moisture well so may not need constant watering.

The intention is to create a hedge that will 1) screen the ugly wall and 2) screen c. 50cm above the wall. Our neighbour's patio is just over the wall and the wall comes to about chin level on their side so screening above the wall is a priority.
I pruned each growing shoot back when planting and they are growing strongly now, with lots of new shoots just below each cut and buds breaking further below each cut.

I've read advice related to cherry laurel to cut these sized plants right back on planting to fill out but my concern is that bay is much slower growing than cherry laural and it would be years before i get screening above the wall. I thinking of cutting say half the shoots back to the level of the top of the wall and half back to 60/70 cm above the ground so that they would fill in lower down. Does this idea make sense.

Thanks