Baby's sleep development is as personal to the baby as their gross motor skill developments - the spectrum of ages these developments happen is very wide.
Instead of age, much better to compare developmental stages. For example:
From first born until 3 or 4 weeks or 3 or 4 months, depending on the child.
Sleep is passive. Mostly baby just wakes for a feed then passively goes back to sleep. As long as calories are maintained, naps can be long in length.
Sleep cycle naps
Out of the newborn phase, slerp develops into cycles of 20-40 minutes (ish) for each sleep cycle.
This phase lasts from "the 4 month sleep regression" (not necessarily at 4 months and not really a regression) and can last anything from a few days to 6 months or longer.
The key to avoid over tiredness is to make naps frequent by reducing awake time. Depending on nap length, awake time of 45-90 minutes is a reasonable expectation
Longer naps, structured routine
The short naps of the above stage can be "worked on" to lengthen, by resetting baby back to sleep when waking. But if you don't do anything, naps will kengthen naturally in time. It just might take longer.
As naps lengthen, awake time between naps also lengthen and you start to develop patterns in the timings, now tger e are fewer naps a day.
Initially this will be a morning nap, afternoon nap and teatime (shoter) power nap too. The first two naps being 1-2h or so in length.
Morning / Afternoon Naps
Again it's developmental, not age related. 2 nap days start anywhere from 4 months up to 12 months, depending on the child. They usually last until 10m-20m old.
Then the single lunchtime nap develops, this can start anywhere from 10 months or 24 months. It can last until the child is 2, 3 or 4 years old.
So..... to answer your question, a decent routine for your 5 month old depends on his sleep development. Primarily, is he still having short naps, or are his naps usually over an hour?