There is a mesh limit per chunk. If you place too many storage blocks/signs/machines in a small space, you might hit the limit and not be able to place anymore.
Anything that isn’t a voxel / block / chiselled block / fluid / grass is included against the limit: torches, machines, storage, doors, signs, etc.
Each chunk is 16m x 16m x full height.
The limit is 512.
If you position complex towers at the corner of 4 chunks then you can increase the limit to 2048 per 4 chunks.
(The limit only exists to stop players filling small areas with complex meshes that would cause a performance issue for all other players.)
Here’s a quick list. I may have forgot a few.
Closed storage
Open storage
Poles
Beams
Shop stands
Plinth
Crafting tables
Machines
Coils
Spark generator
Spark links
Beacons
Campfires
Torches
Signs
Module Signs
Doors
Trap doors
Holiday/event placables
Combustion crops
Portal conduits
Warp conduits
Creative world conduits
Boulders and other rocks
Plants
Chairs and tables.
Non mesh
Grass
Glass panes