When a frangipani is in a pot or bag and the soil is bone dry, you can water it as much as you like and to saturation and your frangipani will enjoy the drink.
While giving too much water is not a problem, giving too much water too often can be a problem. Frangipani roots need air and if they are too wet for too long, the roots will start to rot.
Alternatively, if you are worried about your frangipani not getting enough water, keep in mind that it is very hard to under water a frangipani. Hypothetically speaking, if you wanted a frangipani to die of thirst, you would need it in a pot, bag or very well drained soil, it would need to have a lot of leaves to lose moisture, it would need to be in hot and direct sun for at least several hours a day and you would have to keep rain and other water away from it for several weeks or longer.
If you’re uncertain whether to water a frangipani or not, dig or just poke your finger a centimetre or two into the soil and if the soil has moisture, don’t water at all.
When frangipanis are dormant and aren’t producing new growth, the soil should be kept a little moist for soil health but the frangipani doesn’t need water.