Quite a lot..

Most of my time.

I think that this question can only be answered statistically. Because masturbation behavior depends on age.
I am 74 years old and have been masturbating regularly since I was 9. H. Every day. (For many years I have masturbated 3 times a day, almost every day.) That is 64 years. During this time I have masturbated about 27,595 times. Even now I still masturbate an average of 1.2 times a week. I have the exact numbers because I kept a sex diary out of interest.
I tried (out of interest) to get by without masturbation at the age of 23, I endured 21 days, it was hell.
It seems to me that old longtime masturbators have the same problem.
My problem is that unfortunately I can no longer masturbate every day as I am used to. The reason is that the erection fails and the stimulation to orgasm is not sufficient because the penis has become relatively insensitive.
For me, sex is masturbation.
The masturbation time I spent is relatively easy to calculate since I can reach orgasm in about 3 minutes is 58 days.

I am now 74 years old and have been masturbating regularly since I was 9. H. Every day. (I used to masturbate 3 times a day for many years.) That's 63 years. During this time I have masturbated about 27,595 times. Even now I still masturbate an average of 1.2 times a week. I have the exact numbers because I kept a sex diary out of interest. Take a look at the link, I'm Mr.Z.
http://www.sexarchive.info/TELE/sexology/GESUND/ARCHIV/index.HTM May 1999-2.
I tried (out of interest) to get by without masturbation at the age of 23, I endured 21 days, it was hell. I did this for exactly 21 days and experienced my 1st and only nightly pollution.
By the way: I still haven't found any health problems. So do not worry.
I also prefer to masturbate than I have GV.
With an ejaculation volume of 1.54 grams on average, this results in 27,595 masturbations, 42.5 kilograms corresponds to approximately 4.5 buckets with 10 liters.

Seconded!

Who is keeping count? I'm sure many thousands of times during my life.

Who is keeping count? I'm sure many thousands of times during my life.

In the region of 25,000 wanks in my life. Some quickies and some long edging sessions. Impossible to calculate the amount of time spent, but I guess it's in years.

I have no idea. All I know is, beginning at age 12,
I jerked off whenever (and often wherever) the urge
hit me. I did it at least 3 times a day, every day,
plus every time I bathed or showered. Even while I
was married, I continued to fapregularly, simply
because I was easily aroused.

I think the above sums it up well for me!

It is such a hot question to think about, for me it will be easily thousands and thousands of times, and many, many hours. I've been masturbating since I was about 10, and been enthusiastically doing it many times a week, often many times a day for 26 years now!