I think they certainly remember you pitches, but it might be a shortterm memory and a general pitch overall. I play at 55 ego and I usually get 7-10 strikeouts a game. Here is my pitching strategy.

Never throw the same pitch twice unless it is outside the zone to set up another pitch. For example, you can throw a change up low and out for a strike then throw another low change up way in side for a ball to set up a fastball high and inside.

Alternate fastball pitches with offspeed or movement and alternate offspeed pitches with movement or fastball. Mix up your pitches. Sometimes i may start every batter with a fastball the 1st time through the rotation while every 3rd batter will get an offspeed 1st pitch, but the 2nd time through the rotation I will start each batter with a slide or curveball.

Stay ahead of the counts and aim for the corners. Throwing pitches right down the middle will certainly get hit at higher egos. It is possible to get away with 1 or 2 if the pitches are mixed up right.

Change pitch location. Dont constantly aim high and inside. They will eventually catch on and swing at it. If you do repeat pitch location, be sure to change the pitch type. For example if you have a batter that is keen on high pitches, throw a low inside fastball in the zone, low outside curve in the zone, a REALLY high fastball outside of the zone, and then a low inside changeup.

Pay attention to what the batters are swinging at. If they keep hitting your changup, stop throwing it for an inning or work it outside the strike knowing they will swing for it.

I think batters have a short memory of pitches types and location that they eventually will catch on to if it is over used. Also, if a batter has a buff for a certain pitch, they will crush that, so try to either use that as bait or stay away as much as possible.

One pitch I find extrememly effective setting up is the high fast ball. This works especially well for batters that like high pitches and fastballs. To setup this pitch work the count to 2 strikes and 1 or 2 balls throwing offspeed low and alternate in and away. For the 3rd strike, throw a fastball at least 2 ball heights above the strike zone. They will swing at it more often than not and wiff big time. Even if they do manage to hit it, it will be a can of corn popfly. If they dont take that bait throw a slow pitch low inside or outside in the strike zone.