First please excuse the title – TTS are not my thing.
Some time ago I was visiting an audio colleague and he demonstrated how to alter the tone of the system by altering the down force on the needle.
He accomplished this by placing a small weight on the head of the tone arm.
The TT was alleged to be expensive and the chassis seemed to be made out of a clear Perspex type material.
The tone changes that resulted when adding or removing this weight made was quite marked.

My question is do persons who spin vinyl alter this setting to compensate for thin or conversely bass heavy mastering?

No. Its easier to use EQ.

Changing the weight (VTF) alters the VTA (or rather the stylus rake angle, SRA). For some reason, I prefer to use the manufacturer's recommended downforce, and adjust the VTA via the height of the tonearm.

Here is some info from Analog Magik.com on vertical tracking force.
www.analogmagik.com/vtf

AMR-iFi R&D

Hi james
Although Vertical Tracking Force (VTF) does affect tonal balance, using VTF to adjust tone is not ideal, because Tracking Force is specified by cartridge designer to set 2 main things:

1) The angle of the stylus to the record (SRA) + angle from the cantilever 'pivot' to the record (VTA) - as Citroen mentions.
As you can appreciate, both these should 'match' the 'cut' of the record groove, for low distortion groove tracing.

2) The tracking downforce also relates to the compliance/stiffness of the cartridge 'suspension' - lower compliance cartridges needing more downforce & vice versa.
For stable & accurate tracking.

(Variations in tonal balance when varying VTF are probably due the changes in the cartridge's ability to trace the finer HF groove modulations - ie. SRA & VTA.)

DarkLantern blog - darklanternforowen.wordpress.com

agree with owen, not ideal but useful as a fine tuning tool as there can be so many system variations.

it should be ok as long as you keep within the cartridge manufacturers recommendations.