A quick look at Kodak tech pub J-78 for D-76 shows the slopes of temp vs development time varying by a factor of 1.7 across 6 films at 1:1 dilution. With that much variation using the same developer and dilution, I don't see how you can generalize usefully using the factors you quote across different developer formulations or different films.

Better to go with the charts as PE and others have said.