It does not make any sence at all that some curios are used by everyone and others are just worthless sprites(due to the low LP/huge time amount needed/mental weight). What`s the point of having diversity then?
The idea is pretty simple: tie together LP and time(so, the LP is found by (amount of hours)x(LP-per-hour) where (LP-per-hour) is the same for every curio), OR tie together LP and weight, or time and weight...or all the three. This would lead to the all curios being worthy.