OP the fact that you yourself acknowledge that you're cleaning after masturbation is 'excessive' highlights that there is a issue here, although it may be minor.
Masturbation and sex are perfectly normal activities, that for most people are positive parts of everyday life - good for all round wellbeing, learning about your body and reducing stress. Some people however, can react differently and can find masturbation or their feelings around it or sexuality in general negatively impacts their lives. In some cases it may be worth talking to your doctor if you feel this way.
If it is just about semen then masturbate in the shower or put a condom on for easier clean up.
Often excessive cleaning in relation to an activity is linked to feels that one is dirty or that the activity is shameful and then need to clean themselves, absolve themselves of guilt.
Some people struggle with compulsive behaviours that negatively impact their quality of life. If you find some compulsion is impacting your life negatively then it's worth having a chat to your doctor about it.
In the short term, try to reduce the amount of time you spend in the shower and consider how you are feeling, if you've been down for a while or are struggling with these behaviours then have a chat with your doctor.