Hi,

dropping objects or deleting rows will not reclaim occupied space unless you explicitly run commands to reclaim space.

when your file group is full and no more able to allocate additional space through auto growth or through manual process it stats throwing you error and will not make use of unused free space.

one solution may be to set a small autogrowth for the datafiles may be 1MB, that will not cause the disk to run out of space in single growth.

last solution would be to shrink you data files to release space to OS, but shrink operation creates massive index fragmentation.