That clogging is unlikely. More likely is the septic tank getting overfilled and/or in-tank filter getting clogged.
How long it should be between pumpings varies. Number of people, what non-human stuff they put down the toilet, whether you have a garbage disposal, and what you put down the disposal/drains.
Getting the system pumped earlier than needed is going to cost you some money. But going too long can cost big money. What I think you want to do is to get the system first pumped maybe ((5 years)/(number of people)). Get an experienced owner-operator. Ask neighbors who have been there for a while. Don't go by who advertises more. Ask the person how full it was, and what percent of really needing it it was. Then you can estimate a new interval, and put that on your calendar.
So how much does it cost you to be early so you were only half way to needing it? The $200 to $300 you pay? Nope. Half of that.
If the entrance is hidden, measure the distance of the center from a fixed thing, such as the nearest point on foundation, and a corner of the house. Make notes on a label on your pipes. Then for next time, you would know that the location was the intersection of a line parallel to the foundation, and an arc from the corner of the foundation. But then your system may have visible risers that make that unnecessary.
I would try to remove the dirt without tearing out the bottom of the pit. Are there any holes in the walls? Is that pit on the lower level of the basement or the elevated portion?
=========An alarm============
https://www.basementwatchdog.com/watchdog-water-alarm/
https://www.homedepot.com/p/Basement-Watchdog-Battery-Operated-Water-Alarm-BWD-HWA/100038838
Takes 9-volt battery, and you need to remember to change it. There are others, but that is the only one I have tried.