Number of ads never meets 10 per hour. Actually there used to be a limitation of 4 per hour. That 10 is the absolute maximum that can ever be reached.
The number of ads depends on the campaigns available in your region and on the way you use your browser.
Currently, due to the bear market, global economic crisis, war conflicts, etc, all companies are trying to save costs. There are less and less advertising campaigns.
Actually, most ads nowadays come from brave itself, not so much from Brave customers.
Hints on how to view more ads:
Enabled Brave News and watch them. Ads are randomly embedded in the news list. More you watch Brave News, more the ads you can view.
Get used to open a new tab instead of using the current open one. Ads are shown regularly when you open new tabs.
Ensure that you gave permissions to receive push notifications from Brave. Ads by push notifications are shown regularly. Not so many nowadays due to the reasons above.
Keep your browser active. The system is able to identify if there is a human usage pattern. More the activity, more ads are shown. Keeping the browser open without activity does not grant ads. Simulating activity with bots will not provide many ads either, because it’s a repetitive activity pattern, not a human pattern.
The Crypto market is / was in a bear market and is just strating to recover. Therefore not many advertisers want to advertise right now, hence the reduced number of ads. You can check active campaigns at https://sampson.codes/brave/ads/my_region/
Also, the limit just says that you may get 10 Ads / hour, it in no way suggests that you will get 10 ads for sure.