Luck was on my side as well. Those days IPBL wasn't as competitive as we are now, so I could somehow survive with only like 250k roster, and earn 500k every week.
But now, with the salary floor and the increased competitiveness here, it's much tougher to earn a lot of money each week. If i remember correctly I spent about 3 seasons to tank about 20 million. For Hardcourt it will take probably 5-6 seasons to tank the same amount.
The problem I see with gradually improving the team is that, when you buy good players as you save enough money, the weekly income decreases, so it takes more and more time to save the same amount of money. So in the long term, tanking enough income to buy all the players at once is much faster (but the only drawback is that tanking is reaaaaaally a pain and requires a lot of patience).