I have been using the hard setting for the last couple of weeks. Also, I use yesterday's solution as today's starting word to make it more random. It hasn't made a great deal of difference to the stats.

To my mind, the hard setting, which obliges you to use the revealed letters in subsequent guesses, reduces the skill and makes it more a game of chance. If the first guess gave one blank and four greens, such as

_ A T C H

then the possibilities are

B A T C H
C A T C H
H A T C H
L A T C H
M A T C H
P A T C H
W A T C H

It is just random chance at which point you arrive at the solution and it may be that you run out of goes before you get there. The skill comes from recognising this and choosing words which will eliminate as many of the possible letters in the shortest number of guesses, which can't be done on the hard setting.

DC