There are no statutory limitations. Limitations on the frequency or amount of distributions from the TSP are those imposed by the TSP plan itself (and there are limits).
In-service distributions: https://www.tsp.gov/publications/tspbk12.pdf
Distributions after separation from service: https://www.tsp.gov/publications/tspbk25.pdf
Yes, you are allowed to rollover your Thrift Saving Plan (TSP) to an IRA and there isn't a limit for how often you can do this.
If you roll the funds to a traditional IRA, you have to report the 1099-R on your tax return, but it won't be included in your taxable income.
If you roll the funds to a Roth IRA, you have to report it and it'll be taxable, or partially taxable, in the year the rollover happens.
You may have heard that there is a one per year limit for IRA rollovers. That only applies to certain rollovers where both accounts are IRAs.
There are no statutory limitations. Limitations on the frequency or amount of distributions from the TSP are those imposed by the TSP plan itself (and there are limits).
In-service distributions: https://www.tsp.gov/publications/tspbk12.pdf
Distributions after separation from service: https://www.tsp.gov/publications/tspbk25.pdf