I like to have plenty of tools at hand when I am working on a project, or more correctly when I am working. Mostly I have a few projects on the go at a time in different places in my studio. I like to have tools I need at each station. I have lots of extras of things like spatulas that I use for glue whether it is mastic, or thinset. 
Here's some new spatulas I just got in, and only a couple of dollars each you can afford to get a couple extra. Here's a link to the tools in the Tess-Array store- you'll find these spatulas there.
https://sales.tess-array.com/collections/tools
I always use two spatulas at the end of a gluing or grouting session to clean up. One spatula cleans the other. Give each a good scrape to get all the thinset or mastic off. I stand over my rubbish bag, and give them a good clean off so they are ready to use next time I have the urge to glue something to something.
Karen. 15/12/2018 :)