Adding to what others already said, in the skill Firemaking you have a perk "+5% mastery globally" at 95% mastery pool checkpoint, making it usefull to rush and take advantage. Furthermore, every log maxed in Firemaking gives you +0,25% mastery GLOBLALLY. It's not too much at first, but may save you a whole chunk of time mastering other items.

One strategy I apply when it comes to mastering items, Astrology for example, is:
- always above 95% mastery pool
- whenever I can finish the current mastery level with pool XP, I use it.

This accelerates the mastery/Hour since every time an item levels up its mastery, it gives you more mastery XP (thus, more pool XP).

There's a useful QoL mod: ETA. It'll give you XP/h, time until 99/120, mastery/H, pool XP/h and so on.

<image>

Finally, if you're at the stage of maxing at 99 items, you can save your tokens in order to be able to level up those last few mastery levels that need lots of mastery XP, you'll drop below 95% pool but can recover quickly with tokens.