Force India has been working along with very limited testing, even when they were allowed to test more than now, they didn't have the money to make it to each test.
Vijay is looking smarter every year, as his slimmed down version of an F1 team quietly plugs away and improves year on year. They seem to be very goo at packing a lot into a short test, and getting much out of it.
The bigger teams need to adjust more to thin out, than a small team would to get big.