Don't confuse the requirement to make distributions from the IRA to the trust with whether or not the income from the trust can be distributed to beneficiaries.
Whether the IRA must be distributed within 10 years depends on whether the trust is qualified for look-through to the beneficiaries of the trust, whether all of the beneficiaries are Eligible Designated Beneficiaries, and whether the decedent died before or after the decedent's required beginning date for RMDs.
Whether income to the trust can be distributed to beneficiaries of the trust to have the income taxed on the beneficiaries' tax returns instead of being taxable at trust tax rates depends on the terms set forth in the trust document.
Also, the terms of the trust determine whether the inherited IRA can be split and the respective shares be allocated to the beneficiaries as inherited IRAs maintained for the benefit of the beneficiaries instead of being maintained for the benefit of the trust. (Doing so does not change the RMD requirement that each beneficiary must then meet separately.)
