Figures from the General Teaching Council for Wales (GTCW) show that there is a significant county-by-county variation in the number of teachers applying for grants and bursaries.
Local education authorities and schools have suggested that some hard-pushed teachers could be put off by the work involved in the application process, while others struggle to find supply cover.
But the GTCW said it was not aware of any geographical reasons for the disparity, and said the application process was as simple as possible. Last year, all of its pound;2 million CPD fund was handed out to teachers who applied for grants of up to pound;8,000 to pursue sabbaticals and research, or to form networks with staff in other schools.
This year's pound;2.5m fund is expected to go the same way, but some parts of Wales are attracting more cash than others.
Of the first 395 teachers who have applied in the current financial year, 45 were from Powys, representing 3.3 per cent of all registered teachers working in the authority. This was the highest proportion, and the LEA said it actively encouraged staff to apply.
The lowest was in Blaenau Gwent, where three teachers applied - 0.4 per cent of the teaching staff. The LEA said it too encouraged teachers and offered help with application forms.
Pembrokeshire's figure was also low. Seven teachers, 0.5 per cent, applied in this first batch, which accounted for pound;207,000 of the total fund.
A spokesperson for the authority said: "We are disappointed that relatively few teachers are accessing the funding. It is probable that the significant workload and bureaucracy involved in submitting bids may put them off."
Monmouthshire had the same low application rate of 0.5 per cent. Graham Murphy, head at Archbishop Rowan Williams primary school in Caldicot, said workload was a concern for first-time applicants.
"When you've had your first grant you realise it's not that onerous, but it's difficult to get the first-timers started," said Mr Graham.
In Conwy, where 0.5 per cent applied, Ifor Efans, head of Ysgol Dyffryn Conwy, Llanrwst, blamed paperwork and said: "There's a shortage of supply in the secondary sector which is worse in rural areas. But there's also a lot of paperwork involved with making an application and you need to report back, saying exactly what you've done."
A spokesperson the GTCW said: "We write to every teacher in Wales. The application process was significantly simplified two years ago."