Governments should learn to be frugal with their tech spend, avoid big-bang digital projects and change the budgeting model to finance smaller digestible work that independently adds value, according to the former chief executive of Service NSW, Damon Rees.

Fresh from completing a deep-dive review of the predicted $2.8 billion super business registry project, Mr Rees said up-front funding of big transformation projects through rigid yearly budgets was fraught with risks.