I wonder where in Northern Europe you live, but I live in Finland and belong to Finland landlords organisation. I am no newbie far from that.
It has more to do with that you should never exceed your MAXIMUM recommended total Debt:
The formula for that was in Finland Landlords newest magazine form spring 2021.
Maximum DEBT FORMULA is and this is what they recommend in Finland.
Your work GROSS income/month X (means multiply by) 12.5+ x (MULTIPLY BY) 4.5
+
LANDLORD (+stocks) GROSS income /YEAR (Note not /month) x (MULTIPLY BY) 4.5
Please note in FINLAND we do not have normally SUPER USA Salaries. Normal salary for fulltime worker is usually between 2000-4000 euro in Finland. Of course exceptions exist and 5k euro and 6k euro/month exist.
My salary for work is between 3000-4000 euro/month that is between 3 594,58 United States Dollars and 4 793,20 United States Dollars /month.
I will not tell my landlord income however I am no newbie. The other real estate I own is not in Helsinki I like to buy then in more then one place in the world!
I have investment debt from before. I bought recently a NEW 2022 built project apartment from HELSINKI for 300 000 euro (will not tell exact sell price here) and I will use roughly 80 000 euro own money.
I manage to not got over that maximum debt even with the old debt included when I use roughly 80 000 euro own money. Well and it does not need to be so near the maximum perhaps I want simply to use 80k euro in cash.
It is good if you are clearly below your maximum debt. The above formula was for Finland Europe specific and not valid for whole world. USA salaries are so different so please stick to what your banks recommend in your own country.