What follows are time estimates attributed to different styles and needs. These are not promises but should be fairly close estimates that can be used on similar projects of equivalent scope!
Illustrations with environments
40h from finalized concept.
Renders without environments
24-36h from finalized concept.
4h from finalized concept. Note that these images are usually at a much lower resolution than the pieces shown above.
16h from finalized concept. Estimates might increase if the physical space is irregular or highly demanding.
Detailed Environment Concept
8h to the level shown below.
Thumbnails and Paintovers
Around 2h+ for a sheet of around 12 concepts depending on feedback and requirements. Some of the estimate is attributed to research and reference gathering and can be deducted based on material provided.
Splash screens and Logos
This logo including the back and forth and concept revisions took around 16 hours to get to this level.
Thumbnails and block modeling
Depending on need I often take thumbs straight into primitive block models for painting over. If the final concept is going to be a render or illustration, or is needed to be seen from multiple angles I will heavily insist on spending some time modeling it out. This will save us both time and accuracy!