Depending on application.
On a street or bracket engine, once you set hydraulic lifters - you're thru for the duration.
On a street engine with solids, you can go for weeks. You will get used to hearing the lash opening up as it gets a little louder.
For a race engine, lash setting is required each race (sometimes in later rounds) for consistancy and dependability. Pro racers check lash and valve spring pressure after each run. They are rollers but still solid.
Good luck with your project! Dave