stability in prices means that something that should go for 50k this hour goes for 500k a different one.
This is something you can never change. TL is somewhat based on coincidence. Do the potentially interested managers have the money currently to buy the player. The fact that a player does not sell in the first 3 day listing, does not mean that he will not sell in the next 3 day listing (if the price and listing time are the same). The market changes constantly. Obviously there are better and worse times to list a player, but that's called knowing the market.
I don't understand the fuss about who can be online and who can't be. There is a limit for transfer profitability in 14 weeks. This is not a problem. A successful team needs less than one incoming transfer a month. You can sell players whenever you want. You don't have to be online at the time your player sells. Eventually even the biggest daytraders will get tired. It just is not worth the time you put into it. When they see they can not effectivly do it (not profitable) or get tired, they start to complain, how the game is boring. Yes, this games tempo is ment to be slow. Some can handle it, some can't.