For some, this is the consulting version of Siberia; lost in a hopeless no-man’s land. Without a plan, you'll have very little to do and what you are assigned is often either busy-work or unfulfilling at best. Like a utility player on a sports team, you are sitting in reserve waiting until your skills are needed for another project. It doesn't have to be this way tho. Here are some of the things that you could be doing:
1) Self-promotion: make sure folks know what your interests are, and the sales team know what style of engagements are appealing to you. When was the last time you took an account manager out for coffee or ran a knowledge sharing brown bag? Did you learn something cool yesterday? Run a brown bag or author a thought piece.
2) Helping out: Use the standup to signal that you want to pair with folks. Your peers, state and national leadership teams have a bunch of things they always need help with. Consulting typically involves aspects of leadership, and that can be tiring. Recharge by helping others achieve their goals. It's quite rewarding.
3) Shipping: Create something small, ditch all of the traditional best practice guidelines such as test-driven development or CI and hack away in notepad on a web-server. Get your idea live by the end of the day - i.e. https://noyaml.com/ Taking something from concept to production in a short period is a rush, and I find that the energy compounds. Done right you'll have something to do a brown bag on or show at the next standup.
4) Course-based learning: It's not for me, but if it works for you then awesome. Just make sure you ship something or use the Feynman technique so that time doesn't go to waste.
5) Social: take the opportunity to get out into the field and see folks who you usually don't usually get to spend time with. That includes peers within your company and the broader community - ie customers.
6) Go wide (or deep) on foundational topics like systems administration which like software development the Single-responsibility-principle is everywhere; you're always fighting state. If you are sick of technology churn then why not master a foundational computer science topic or study a foundational academic paper? - https://github.com/papers-we-love/papers-we-love
7) Recharge, consulting can be stressful. Use this time to reflect, replenish and action whatever tasks are outstanding so that you can focus 100% on your next client when they come along.