Hi there
A more common routine at 4 months is to have just 3naps. A times are as a guidance 1hr 45 to 2hrs which is not far from the A times you mentioned but at this age 10 mins can make quite a difference to a LO and could mean the difference between transitioning between cycles and having a longer nap or taking a shorter nap due to being a little bit UT (under tired).
As you are already comfortable with 1hr 52 I would suggest increasing A times to 2hrs and holding at that time. If one of the A times is a little shorter (for instance if you always get a good long nap of almost 2 hrs on the A time you are using which is a little under 2hrs) that's fine but then try to hold out after a good nap to the full A time of 1hr 52 to 2hrs to encourage the next nap to be equally as long.
With the slightly longer A time and the longer naps you will hopefully get through the day on 3 naps, there is no harm in doing an EBT (early bed time) to prevent the last A time getting too long. Around nap drops times EBT is very useful to help avoid OT.
A warning too, at this age A times increase quite rapidly. At 6 months the A time will be as long as 3hrs...you are only about 6 wks away from this and time flies. 6 months is usually the time when naps drop from 3-2 so there is another transition phase for that too.
hope this helps