To assess the appropriate level of hybrid bond issuance for Italgas S.p.A., we analyze its financial position and strategic requirements based on the 2022 annual report data.

**1. Financial Position and Risk Profile:**
Italgas operates as a regulated utility, a sector that typically provides stable, predictable cash flows. The company has a significant and growing asset base, with "Intangible Assets and Goodwill" increasing from approximately 7.47 billion EUR to 8.51 billion EUR. This suggests a continuous, heavy investment strategy typical for utility infrastructure expansion.

**2. Leverage and Liquidity:**
- Total Equity 2023: 2.39 billion EUR.
- Long-term Financial Liabilities 2023: 6.40 billion EUR.
- Cash and Cash Equivalents 2023: 452 million EUR (a significant decrease from 1.39 billion EUR in 2022).
- The company’s net debt remains substantial relative to its equity, and the increased capital expenditure (as evidenced by the growth in intangible assets and investing activities) necessitates consistent access to capital. 

**3. Strategic Requirements:**
The company is currently in a phase of high capital intensity, reflected in substantial investment spending and a shift toward a higher debt load to fund this infrastructure growth. While the regulatory environment for gas utilities generally allows for cost recovery, the transition to sustainable energy and large-scale infrastructure projects often requires significant upfront capital. 

**4. Hybrid Assessment:**
- **Refinancing/Capex:** The company faces heavy investment needs. While its rating profile is likely investment grade, the leverage metrics are pressured by the high debt levels required for its infrastructure expansion.
- **Cost/Benefit:** Given the current market environment (rising interest rates compared to 2020-2021) and the need to maintain strong credit metrics while sustaining capital programs, a moderate to significant hybrid issuance strategy is appropriate.
- **Guideline Matching:** The company demonstrates a pattern of heavy capital expenditure and needs to preserve its rating while maintaining flexibility. A 7.5% allocation balances the need for leverage optimization with the reality of current financing costs, providing meaningful improvement to leverage metrics without reaching the extreme of 15% which is typically reserved for companies facing immediate, transformational downgrade risks.

Given the moderate leverage pressure and the need to fund ongoing infrastructure projects, a 7.5% allocation is a prudent strategy to balance rating stability with cost-of-capital considerations.

<answer>7.5%</answer>