Not sure if this is a bug, or intended, but I was mining Iron at level 8 and getting 149 PPs for unsuccessful and 248 PPs for success. I leveled up to 9 and the PPs I was getting dropped by one. Previously I gained more PPs per attempt after leveling up.
(04:43:35) >You start to dig.
(04:43:45) >You've got some Iron Ore!
(04:43:45) >You gained 248 experience points and 1 progression point!
(04:43:45) >You've gained some practice points in Mining.
(04:43:51) >You start to dig.
(04:44:01) >You were not successful.
(04:44:01) >You gained 149 experience points and 1 progression point!
(04:44:01) >You've gained some practice points in Mining.
(04:44:04) >You start to dig.
(04:44:14) >You were not successful.
(04:44:14) >You gained 149 experience points and 1 progression point!
(04:44:14) >You've gained some practice points in Mining.
(04:44:14) >You've ranked up in Mining!
(04:44:17) >You start to dig.
(04:44:27) >You were not successful.
(04:44:27) >You gained 148 experience points
(04:44:35) >You start to dig.
(04:44:45) >You were not successful.
(04:44:45) >You gained 148 experience points and 1 progression point!
(04:44:48) >You start to dig.
(04:44:58) >You've got some Iron Ore!
(04:44:58) >You gained 247 experience points and 1 progression point!