I agree with the above post by Breadfish, but....isn’t ALL SEX on a spectrum? Doesn’t everyone change? Our sexual preferences change with time too. Change is constant.
I’d also like to point out that OP seems to have developed a “habit” or cycle for masturbating. We do what is comfortable & produces results for us. Satisfaction.
The same cycle, with no change, can also result in boredom.
It’s classic conditioning which can happen in our sex lives too. Trying different things can break this conditioning & broaden our satisfaction....if we’re willing to try.