This is a good question - you don't have to take all of your tax-free cash in one go.
Providing you have the right type of pension e.g. SIPP which has the flexibility, you can take part of your pension as tax free cash
I explain this as "Salami Slicing" - every you time you cut off a slice of pension you can take 25% TFC e.g. £10,000 will pay £25K TFC and £100K will pay £25K
In practical terms you end up with two types of pension; some untouched pension (i.e. full 25% option still available) and some in drawdown (no more TFC)
It sounds complicated but a good adviser (e.g. me) can explain the advantages and disadvantages.