Geoff Willis believes formula one made a "mistake" in completely banning in-season track testing.The ban was imposed to cut costs, theoretically benefitting the smallest teams like HRT, where Briton Willis is the technical consultant.But he argues that the complete absence of testing means money is instead spent on expensive simulation technology."The mistake, for me, is that while it was sensible to stop unrestricted testing, a better balance would have been to have certain fixed testing times common to all teams and wrap up a commercial operation around it," he said.Willis also surprisingly backs the return next year of a 107% qualifying rule, even though HRT would have been excluded from some races if it had applied in 2010."I think you have to expect the teams to operate at a certain level, that's what we want from formula one," he said, advocating an even harsher 105% rule."Obviously we would be a little bit uncomfortable with 105 per cent in our current position but it wouldn't surprise me in the future. It's just the nature of formula one," said Willis.