Until the time you need to switch the light back on again. :-(
I've had the same sort of trouble with the last remaining fluorescent fitting that I couldn't upgrade to a "Quickstart"(tm) transformer ballast on account I couldn't get the older style compatible T12 tubes for this 5 foot fitting. The problem is clearly down to shite quality starter switches and I eventually sorted it out by buying enough of them from which to choose a working one (about 4 or so 'new' ones to add to my existing collection of two or three).
Even so, it takes some 5 to 10 seconds before the tube will strike, strangely, sans the disco strobe effect - it just sits there with the ends glowing (or not) before suddenly striking to full uninterrupted brightness. As a consequence, it tends to be left switched on for the whole evening.
 One of these days, when we finally start seeing 200LPW LED equivalents to the 150W incandescent GLS light bulb, I'll revert it back to the ceiling pendant fitting it had before this 'spare bedroom' became my office/workshop some 20 years ago.
The unavailability of Quickstart compatible tubes hit home over a decade ago with the shorter 4 foot variety so the last remaining 4 foot Quickstart fitting (in the basement) is now relying on the very last working compatible tube until it too finally expires (they last a bloody sight longer in Quickstart fittings - 16000 hours versus 7000 hours or so in a switch start fitting).
Fluorescent luminaires are the only sane choice in some locations such as kitchens (and my basement) for their non-glare, shadowless illumination properties. Until recently, they were still top dog for energy efficient lighting (still are compared to the older stock of LED Tubes being foisted on the great unwashed consumer in most retail stores).
However, once I start to see 125LPW (or better) 300 to 360 deg LED tube replacements, I'll upgrade the last of my fluorescent fittings. Until then, I don't see much point in wasting time and money on a mediocre 'upgrade'. Alternatively, large area ceiling panel luminaires might make a more suitable substitute for the humble fluorescent tube fitting. At the end of the day, it all boils down to their cost effectiveness.
Johnny B Good
Johnny B Good