5-10 seconds is silly you would barely even be able to load up the dig screen and click the dig button in that amount of time. They clearly last a set number of turns the exact number I have no idea. Afortunado are time based from my experience not sure on the exact amount on those either.
it`s a matter of luck.. as the game say`s you feel lucky but in some instances the luck is only a feeling .. i have found that suerte`s (major) work for 5-10 seconds but not alway`s as i said sometimes you arn`t lucky but you feel lucky and the game doesn`t give you any luck :)
minor suerte`s are much less usefull and i mix them in with the major`s i conclude that minor suerte`s only work for about 2-5 seconds or less so however many turns you can try and use in those few seconds will be the outcome but, there is still the factor of feeling and actually being lucky
Use a Major Suerte every 50 turns while digging at rare or uncommon time..
Dunno about minors I never bothered to use them..
Suerte`s are far better as you can dig them up, instead of having to fuse them.