I don't see that it's any big, bad secret. I've occassionally used it to finish production (to pick up a task that I want) and to purchase the additional task, if it's a close race. It's just a resource. Everyone can get t-cash free; I generally get anywhere from 4-20 t-cash at the House of Luck (I wait until I have the full amount); you can sometimes get it filling a plane as well as the regatta rewards. I've never used it on trains or ships because I used the dealer to buy ore, to make ingots, to upgrade both trains and ships. At 50% upgrade, trains take about 2.5 hours and ships from 2 hours (Frutus Island) to 4hrs 30min (Tropica). I always hire the dealer and use extra t-cash to buy additional market boxes (have about 80 now). BTW: I'm at level 117 and have spent less than $12 to buy t-cash (for special decorations tied with a t-cash offering). To me, this is a game of patience and strategy and I'm also too cheap to spend $$$ when I don't have to.