No hard or fast rule abt this.
Few years back in LW, I was allowed to bet 100 for a "1 pays 4" insurance on a 200 initial bet.
It's depends by the house, your initial bet and insurance payout. For example your initial bet is 200, insurance payout "1 pays 4", usually they let your bet max up to 60.
So how's the situation in LW lately? Have not been there since march. Any significant changes? I know those private si kee pi dealers all disbanded liao, one drives a cab, one working as a dealer in SANDS.